Learn Python From Scratch - Functions & Strings

<div dir="ltr" style="text-align: left;" trbidi="on"> <div class="MsoNormal" style="text-align: justify;"> <span style="font-size: 12.0pt; line-height: 107%; mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin; mso-fareast-font-family: "Adobe Fan Heiti Std B";">Python – Functions and strings<o:p></o:p></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="font-size: 12.0pt; line-height: 107%; mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin; mso-fareast-font-family: "Adobe Fan Heiti Std B";"><br /></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;">Hi guys, hope you all are catching along with previous Learn Python From Scratch tutorial, in this post you will come across python functions and string operations. <span style="font-size: 12pt;"><o:p></o:p></span></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="font-size: 12.0pt; line-height: 107%; mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin; mso-fareast-font-family: "Adobe Fan Heiti Std B";"><br /></span></div> <div class="MsoNormal" style="text-align: justify;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhe6uYknTgHztRs5a1cT7KWlcC9IRCyFijc3WX3rB5BEstamS2iIua_xMtQ7kCzoUGIgy0fcHif_OYpq6HOANJzDpZjBIb4miyqh7jV_rttHphAiPurNfqS5YPdebPf8SLNbOtLvDOPE0M/s1600/function1.PNG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em; text-align: center;"><img border="0" data-original-height="324" data-original-width="754" height="136" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhe6uYknTgHztRs5a1cT7KWlcC9IRCyFijc3WX3rB5BEstamS2iIua_xMtQ7kCzoUGIgy0fcHif_OYpq6HOANJzDpZjBIb4miyqh7jV_rttHphAiPurNfqS5YPdebPf8SLNbOtLvDOPE0M/s320/function1.PNG" width="320" /></a><span style="line-height: 107%;"><b><span style="font-size: large;">Functions</span></b><span style="font-size: 12pt;"> </span>are a construct to structure programs. They are known in most programming languages, sometimes also called <b>subroutines</b> or <b>procedures</b>. Functions are reusable piece of code that can be invoked as many times as required in the program and perform certain task.<o:p></o:p></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;"><br /></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;">In Python a function is some reusable code that takes arguments(s) as input, does some computation, and then returns a result or results. We define a function using the def reserved word. We call/invoke the function by using the function name, parentheses, and arguments in an expression </span></div> <div class="MsoNormal" style="text-align: justify;"> <br /></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;"><span style="font-size: large;"><b>There are two kinds of functions in python.</b></span><o:p></o:p></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;"><span style="font-size: large;"><br /></span></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;">-  Built-in functions that are provided as part of Python library - print(), input(), type(), float(), int()<o:p></o:p></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;">-  Functions that we define ourselves and then use<span style="font-size: 12pt;"><o:p></o:p></span></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;"><span style="font-size: large;"><br /></span></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;"><b><span style="font-size: large;">Building our own function:</span></b></span></div> <div class="MsoNormal" style="margin-left: 18.0pt; text-align: justify;"> </div> <ul> <li>We create a new function using the def keyword followed by optional parameters in parentheses</li> <li>We indent the body of the function</li> <li>This defines the function but does not execute the body of the function</li> </ul> <br /> <div class="MsoNormal" style="text-align: justify;"> <span style="font-size: 12.0pt; line-height: 107%; mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin; mso-fareast-font-family: "Adobe Fan Heiti Std B";"> </span></div> <br /> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVRFzalGWUAur38UnRmnv-21QvOKcc0a92uCMdKmMbPzJzfsKvX9VE-8meJrV66X8dKqB3fSzT1j6yIrwzI8wAyDkJdMuyxO_vYV38teMfPdpijM0V_-TaZ8UskDABCaMM_JjB0tABtPk/s1600/function.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="427" data-original-width="574" height="296" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVRFzalGWUAur38UnRmnv-21QvOKcc0a92uCMdKmMbPzJzfsKvX9VE-8meJrV66X8dKqB3fSzT1j6yIrwzI8wAyDkJdMuyxO_vYV38teMfPdpijM0V_-TaZ8UskDABCaMM_JjB0tABtPk/s400/function.PNG" width="400" /></a></div> <div class="MsoNormal" style="text-align: justify;"> <br /></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;"><b><span style="font-size: large;">Docstring:</span></b><span style="font-size: 12pt;"> </span>The first string after the function header is called the docstring and is short for documentation string. It is used to explain in brief, what a function does.<o:p></o:p></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;">Although optional, documentation is a good programming practice. Unless you can remember what you had for dinner last week, always document your code.<o:p></o:p></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;">In the above example, we have a docstring immediately below the function header. We generally use triple quotes so that docstring can extend up to multiple lines. This string is available to us as __doc__ attribute of the function. For example:<o:p></o:p></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;"><br /></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;">def greet(name):<o:p></o:p></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;">            """This function greets to the person passed in as parameter"""<o:p></o:p></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;">            print("Hello, " + name + ". Good morning!")<o:p></o:p></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;"><br /></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;">Try running the following script with the below addition: <o:p></o:p></span></div> <div class="MsoNormal" style="text-align: justify;"> print(greet.__doc__)</div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;"><br /></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;">You will get the output on your console as,</span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;">>>> This function greets to the person passed into the name parameter<o:p></o:p></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;"><br /></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;">This is the end of the first topic of discussion in this post which was functions. Now let’s see what does <b>"Strings"</b> in python have to offer to a programmer.<span style="font-size: 12pt;"><o:p></o:p></span></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="font-size: 12.0pt; line-height: 107%; mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin; mso-fareast-font-family: "Adobe Fan Heiti Std B";"><br /></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;"><span style="font-size: large;">A <b>String,</b></span></span></div> <div class="MsoNormal" style="text-align: justify;"> </div> <ul> <li>contiguous series of characters delimited by single or double quotes<span style="font-size: 12pt;">. </span></li> <li>A string literal is initialised with values in quotes. </li> <li>Python don’t have any separate data type for characters, so they are represented as a single character string. </li> <li>Strings in python are immutable, i.e. that once string is created it can’t be modified.<span style="font-size: 12pt;"> </span></li> <li>For strings, + operator means “concatenate”. </li> <li>When a string contains numbers, it is still a string but they can be converted into numbers int().</li> </ul> <br /> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiftGDdj8byMkT-VYxn1eORAPWGcyBCdG4e_DzsBKWWrpPdz5z8x5aR2gkVT5RHGvzpgq1iwm01NJ8FgKfwRai6yKhzv8aZxhPdz5aAPT8PgjXA4_sGWeNLtV1FOdvAuL9YnWjXJWWe764/s1600/string.PNG" imageanchor="1" style="font-size: medium; margin-left: 1em; margin-right: 1em; text-align: left;"><img border="0" data-original-height="382" data-original-width="759" height="201" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiftGDdj8byMkT-VYxn1eORAPWGcyBCdG4e_DzsBKWWrpPdz5z8x5aR2gkVT5RHGvzpgq1iwm01NJ8FgKfwRai6yKhzv8aZxhPdz5aAPT8PgjXA4_sGWeNLtV1FOdvAuL9YnWjXJWWe764/s400/string.PNG" width="400" /></a></div> <div class="separator" style="clear: both; text-align: center;"> <br /></div> <div class="MsoNormal" style="text-align: justify;"> <span style="font-size: 12.0pt; line-height: 107%; mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin; mso-fareast-font-family: "Adobe Fan Heiti Std B";"></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;">We can get at any single character in a string using an index specified in square brackets. The index value must be an integer and starts at zero. If you try to attempt to access using index beyond the length of the string python gives a traceback. The built-in function to check the length of the string is len(). The string operations offered by python are:<o:p></o:p></span></div> <div class="separator" style="clear: both; text-align: center;"> <br /></div> <br /> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEghxQdZF-YIMJu1mXnZFb5Ny5qaFPVU3tewIe0HkpdP6TWFmQZA42mkkVVjaZ_dvYIcap8Lh9Fi414UyAtuq2SRDYlQTyCgFpL9KO_na7IVzi1-FKmNcdF9II7hD4Ncwf1DyFjov9r9E-8/s1600/prefixes_str.PNG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="230" data-original-width="552" height="133" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEghxQdZF-YIMJu1mXnZFb5Ny5qaFPVU3tewIe0HkpdP6TWFmQZA42mkkVVjaZ_dvYIcap8Lh9Fi414UyAtuq2SRDYlQTyCgFpL9KO_na7IVzi1-FKmNcdF9II7hD4Ncwf1DyFjov9r9E-8/s320/prefixes_str.PNG" width="320" /></a></div> <div class="MsoNormal" style="text-align: justify;"> The method startswith() checks whether string starts with str, optionally restricting the matching with the given indices start and end. </div> <div class="MsoNormal"> <span style="line-height: 107%;"><br /></span></div> <div class="MsoNormal"> <span style="line-height: 107%;">It has the following syntax:<o:p></o:p></span></div> <div align="center" class="MsoNormal" style="text-align: center;"> <span style="line-height: 107%;"><b>str.startswith(str, beg=0,end=len(string))</b>;<o:p></o:p></span></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> <br /></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-WLiMm9fb5zKdefiMYLLM32BkDKxqkmQsf2KwJ0RReHIGb9GrHIPL0LrwY2c5UVkeBfPVtX3wRBViKlsTM985n4pL-BY4iuiU0bPU8G1VZGGeLmNkeye3wElo7BO2uJqj8r2YSSiUPz0/s1600/replace_str.PNG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="261" data-original-width="474" height="176" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-WLiMm9fb5zKdefiMYLLM32BkDKxqkmQsf2KwJ0RReHIGb9GrHIPL0LrwY2c5UVkeBfPVtX3wRBViKlsTM985n4pL-BY4iuiU0bPU8G1VZGGeLmNkeye3wElo7BO2uJqj8r2YSSiUPz0/s320/replace_str.PNG" width="320" /></a></div> <br /> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> <br /></div> <div style="text-align: justify;"> The replace() function is like a “search and replace” operation in a word processor. It replaces all occurrences of the search string with the replacement string. </div> <div class="MsoNormal"> <span style="line-height: 107%;"><o:p></o:p></span></div> <br /> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRYqfGnyql8k6bLrfmmtiBk2HIrI_w7M0fDJMj7Fz-n9I_GePYlMCKnougBwa3B0d27nK_kCOOWiLT4yjKgk6omj6ztabr9-pd7WBj2uI1fkZrQ2jFtoVCZpq3Mb3fN6N3a-YI5Br7-zg/s1600/search_str.PNG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="399" data-original-width="432" height="295" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRYqfGnyql8k6bLrfmmtiBk2HIrI_w7M0fDJMj7Fz-n9I_GePYlMCKnougBwa3B0d27nK_kCOOWiLT4yjKgk6omj6ztabr9-pd7WBj2uI1fkZrQ2jFtoVCZpq3Mb3fN6N3a-YI5Br7-zg/s320/search_str.PNG" width="320" /></a></div> <br /> <br /> <div class="MsoNormal"> <span style="line-height: 107%;"><br /></span></div> <div class="MsoNormal"> <span style="line-height: 107%;"><br /></span></div> <div class="MsoNormal"> <span style="line-height: 107%;"><br /></span></div> <div class="MsoNormal"> <span style="line-height: 107%;">1. We use the <b>find()</b> function to search for a substring within another string. </span></div> <div class="MsoNormal"> <span style="line-height: 107%;"><br /></span></div> <div class="MsoNormal"> <span style="line-height: 107%;">2. <b>find()</b> finds the first occurrence of the substring. </span></div> <div class="MsoNormal"> <span style="line-height: 107%;"><br /></span></div> <div class="MsoNormal"> <span style="line-height: 107%;">3. If the substring is not found, <b>find()</b> returns -1.</span><o:p></o:p></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgicuyL99-nsFjI7CwoKbGDSm0SFR6N1hTJ9YOry9TrubbQ1CeS8MPuLLtX-LmdkQA9oTvMirPo9hSSUkSw_IIjE9vvyE973HhpQ9ao7GCoKEv9x3Cg9DWBxQqjbcYDH11wwE7q4mYiRQA/s1600/slice.PNG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="333" data-original-width="492" height="216" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgicuyL99-nsFjI7CwoKbGDSm0SFR6N1hTJ9YOry9TrubbQ1CeS8MPuLLtX-LmdkQA9oTvMirPo9hSSUkSw_IIjE9vvyE973HhpQ9ao7GCoKEv9x3Cg9DWBxQqjbcYDH11wwE7q4mYiRQA/s320/slice.PNG" width="320" /></a></div> <br /> <br />  <span style="text-align: justify;">Slicing a string is a powerful tool in python strings wherein we can extract some part of a string. Slicing is performed using colon operator. We extend the square-bracket syntax a little, so that we can specify not only the starting position of the piece we want, but also where it ends. If we leave off the first number or the last number of the slice, it is assumed to be the beginning or end of the string respectively.</span><br /> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 17.12px;"><o:p></o:p></span></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsCeZ4NEEConHExaxlTYnfMsVGvW2Rmr2FAjI-q0Z6p6UevGr8tj4pJJsPBP4REdzVPrBnKUKX0vp6_xBuBmlvc-r-8UQ97zgEWs-gGlkvkW-2wvrMHJA6y4VkKl1_AH5C15El5TWe9Q8/s1600/Str_comp.PNG" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="322" data-original-width="771" height="133" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsCeZ4NEEConHExaxlTYnfMsVGvW2Rmr2FAjI-q0Z6p6UevGr8tj4pJJsPBP4REdzVPrBnKUKX0vp6_xBuBmlvc-r-8UQ97zgEWs-gGlkvkW-2wvrMHJA6y4VkKl1_AH5C15El5TWe9Q8/s320/Str_comp.PNG" width="320" /></a></div> <br /> You can use ( > , <, <= , <= , == , !=  ) to compare two strings.<br /> <br /> Python compares string lexicographically i.e using ASCII value of the characters.<br /> <div class="MsoNormal"> <o:p></o:p></div> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiftGDdj8byMkT-VYxn1eORAPWGcyBCdG4e_DzsBKWWrpPdz5z8x5aR2gkVT5RHGvzpgq1iwm01NJ8FgKfwRai6yKhzv8aZxhPdz5aAPT8PgjXA4_sGWeNLtV1FOdvAuL9YnWjXJWWe764/s1600/string.PNG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><br /></a> <br /> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgulZsjZUxxxr3oBCFHhTTCAXrakxUSkpCDGIpiMyiHc5CDEtVRdH6KWuEWFVR6zqF7KBHFsKJwOF3LDBqnFSsIXW6Q-UJMhIFtdOk_jWdqF3cgvzj5EB8OPNT_DyDEc2v45m6unE3XICk/s1600/strip_str.PNG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" data-original-height="260" data-original-width="384" height="216" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgulZsjZUxxxr3oBCFHhTTCAXrakxUSkpCDGIpiMyiHc5CDEtVRdH6KWuEWFVR6zqF7KBHFsKJwOF3LDBqnFSsIXW6Q-UJMhIFtdOk_jWdqF3cgvzj5EB8OPNT_DyDEc2v45m6unE3XICk/s320/strip_str.PNG" width="320" /></a></div> <div class="MsoNormal"> <span style="line-height: 107%;"><br /> <!--[if !supportLineBreakNewLine]--><br /> <!--[endif]--><o:p></o:p></span></div> <div class="MsoNormal"> <span style="line-height: 107%;"><br /></span></div> <div class="MsoNormal"> <span style="line-height: 107%;">1. Sometimes we want to take a string and remove whitespace at the beginning and/or end.<o:p></o:p></span></div> <div class="MsoNormal"> <span style="line-height: 107%;"><br /></span></div> <div class="MsoNormal"> <span style="line-height: 107%;">2. lstrip() and rstrip() remove whitespace at the left or right.<o:p></o:p></span></div> <div class="MsoNormal"> </div> <div class="MsoNormal"> <span style="line-height: 107%;"><br /></span></div> <div class="MsoNormal"> <span style="line-height: 107%;">3. strip() removes both beginning and ending whitespace.</span><o:p></o:p></div> <div class="MsoNormal" style="text-align: justify;"> <br /></div> <div class="MsoNormal" style="text-align: justify;"> <br /></div> <div class="MsoNormal" style="text-align: justify;"> <br /></div> <div class="MsoNormal" style="text-align: justify;"> <span style="line-height: 107%;"><span style="font-size: large;">Here are some of the most common string methods,</span></span></div> <div class="MsoNormal" style="margin-left: 18.0pt; text-align: justify;"> </div> <ol> <li><b>s.lower(), s.upper()</b> -- returns the lowercase or uppercase version of the string</li> <li><b>s.strip() </b>-- returns a string with whitespace removed from the start and end</li> <li><b>s.isalpha(), s.isdigit(), s.isspace().</b>.. -- tests if all the string chars are in the various character classes</li> <li><b>s.startswith('other'), s.endswith('other')</b> -- tests if the string starts or ends with the given other string</li> <li><b>s.find('other')</b> -- searches for the given other string (not a regular expression) within s, and returns the first index where it begins or -1 if not found</li> <li><b>s.replace('old', 'new')</b> -- returns a string where all occurrences of 'old' have been replaced by 'new'</li> <li><b>s.split('delimiter')</b> -- returns a list of substrings separated by the given delimiter. The delimiter is not a regular expression, it's just text. 'aaa,bbb,ccc'.split(',') -> ['aaa', 'bbb', 'ccc']. As a convenient special case s.split() (with no arguments) splits on all whitespace chars.</li> <li><b>s.join(list)</b> -- opposite of split(), joins the elements in the given list together using the string as the delimiter. e.g. '---'.join(['aaa', 'bbb', 'ccc']) -> aaa---bbb---ccc</li> <li><b>s.replace(str1, str2)</b> – this function is like search and replace operations where ot replaces all occurences of the search string str1 by the replacement string str2.</li> </ol> <div class="MsoNormal" style="text-align: justify;"> So here we are, at the end of the post, lets summarize the topics we have seen today. Functions: What are they? Why are they used? How can we define a function? Strings: What are they? How are they used and various methods that provide some meaningful operations perform-able to these string. This concludes the post, stay tuned for the next post on the topic of file operations, until then guys enjoy your time browsing through other posts in the blog!! Please leave your questions in the comments section if any. </div> </div>

Tutorials Learn Python From Scratch - Functions & Strings

Python – Functions and strings Hi guys, hope you all are catching along with previous Learn Python From Scratch tutorial, in this post...

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Learn Python from Scratch - Conditional Execution

<div dir="ltr" style="text-align: left;" trbidi="on"> <br /> <div class="MsoNormal" style="text-align: justify;"> <br /></div> <div class="MsoNormal" style="text-align: justify;"> Ola pythonista's, so this is a follow up of the previous post which was on the introduction of python. Here, I’m going to talk about Conditional execution and iterations in python. Hope you would find it interesting to browse.<o:p></o:p></div> <div class="MsoNormal" style="text-align: justify;"> <br /></div> <div class="MsoNormal" style="text-align: justify;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhZDJ7-NJ0dvU0AVIzJX5BjE-sgsf6Q-3niLMUntG7VofImNgX1Mq2AeL3sKjy6nTvxFcHpk9nYZc1o1PCThvvnlvO95xIYJ0gTeIjh7HD-8qzWq_SHpn-n6cSo82K1aUSDUP7JxVbZjew/s1600/if.PNG" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em; text-align: center;"><img border="0" data-original-height="417" data-original-width="782" height="170" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhZDJ7-NJ0dvU0AVIzJX5BjE-sgsf6Q-3niLMUntG7VofImNgX1Mq2AeL3sKjy6nTvxFcHpk9nYZc1o1PCThvvnlvO95xIYJ0gTeIjh7HD-8qzWq_SHpn-n6cSo82K1aUSDUP7JxVbZjew/s320/if.PNG" width="320" /></a>There are many conditional constructs in python, and the first one we are going to see is the unidirectional branching statement, the prodigal construct: “if”.<o:p></o:p></div> <div class="MsoNormal" style="text-align: justify;"> <br /></div> <div class="MsoNormal" style="text-align: justify;"> An if statement precedes with a condition that is checked and is recouped to a boolean expression and if it’s results to true then a set of statement are executed otherwise they’re skipped and the instructions after the construct body is executed. <o:p></o:p></div> <div class="MsoNormal" style="text-align: justify;"> Boolean expressions in python use the following relational operators:</div> <div class="MsoNormal" style="text-align: justify;"> <o:p></o:p></div> <div style="margin-left: 1em; margin-right: 1em; text-align: left;"> </div> <div class="MsoNormal" style="text-align: justify;"> <br /></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi8iW1etxVQ-lztvQqCdFQ-BIPt8SDPZx55lF3gA4X_Uj_xyNP9IDOd1t9Qc9SpD5KBqQU_Ww14jmmNG4B4LlewO-iAthRDLZQvsNG_UxNofHUioMjWInQQU33xC3cUIGVmg0mUAtKckLw/s1600/relational_operators.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="291" data-original-width="403" height="231" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi8iW1etxVQ-lztvQqCdFQ-BIPt8SDPZx55lF3gA4X_Uj_xyNP9IDOd1t9Qc9SpD5KBqQU_Ww14jmmNG4B4LlewO-iAthRDLZQvsNG_UxNofHUioMjWInQQU33xC3cUIGVmg0mUAtKckLw/s320/relational_operators.PNG" width="320" /></a></div> <div class="separator" style="clear: both; text-align: center;"> <br /></div> <div class="MsoNormal" style="text-align: justify;"> Indentation is an important prospect of python programming language as the language doesn’t use the usual flower braces to represent a construct body as in other high-level languages as C++ or Java and hence an increase indent after conditional or looping statement indicate the body of the construct and the indent is maintained to indicate the scope of the block. To get back to level of the conditional or iteration statement we reduce the indent to indicate the end of the block. <o:p></o:p></div> <div> <br /></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikDEbuohK3Gy7m8Gbp3OgKYgHBQkhqpEp5FvVyKTCJF29WhXOEe5jEOVnjkRqA7kTQ2WwT_uk7IkljCiOku-1PsZ9WI_rWgD6RJtwptinWEGVDewyGyQ9IS_Omx35sa6nCpGCpNZaWVCA/s1600/meme1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="525" data-original-width="790" height="212" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikDEbuohK3Gy7m8Gbp3OgKYgHBQkhqpEp5FvVyKTCJF29WhXOEe5jEOVnjkRqA7kTQ2WwT_uk7IkljCiOku-1PsZ9WI_rWgD6RJtwptinWEGVDewyGyQ9IS_Omx35sa6nCpGCpNZaWVCA/s320/meme1.jpg" width="320" /></a></div> <div style="margin-left: 1em; margin-right: 1em; text-align: right;"> </div> <div class="MsoNormal" style="text-align: justify;"> <br /></div> <div class="MsoNormal" style="text-align: justify;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiztEKIq6SlVkam175_uK2DEioTShQLJVSJv6eirf7RyOhpSHh_OGKBrdpn3cSYum5vr_FxEqYlLpnshYQZPFQMjimlSfs2JbrCn3iqW5CSekpGXsxtcFQPYood4030-7uBFIjGz_HwYc0/s1600/meme3.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em; text-align: center;"><img border="0" data-original-height="692" data-original-width="720" height="307" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiztEKIq6SlVkam175_uK2DEioTShQLJVSJv6eirf7RyOhpSHh_OGKBrdpn3cSYum5vr_FxEqYlLpnshYQZPFQMjimlSfs2JbrCn3iqW5CSekpGXsxtcFQPYood4030-7uBFIjGz_HwYc0/s320/meme3.png" width="320" /></a>Two-way decisions are possible in python by using if-else construct wherein if the condition evaluates to true a set of statement are executed otherwise the body in the else construct is executed and finally executed the rest of the instructions after the conditional construct. Below is a snippet that depict two-way decision.<o:p></o:p></div> <div class="MsoNormal" style="text-align: justify;"> //flowchart and snippet <o:p></o:p></div> <div class="MsoNormal" style="text-align: justify;"> <br /></div> <div class="MsoNormal" style="text-align: right;"> </div> <div class="MsoNormal" style="text-align: justify;"> Mutli-branching decision is possible by using an if-elif-else construct, where in if the condition evaluates to true executes a set of statements and skips execution of the rest of the conditional construct otherwise evaluate the next condition that precedes the elif statement and if that evaluates the condition to true then a set of instructions are executed otherwise executes the statements in the else body.</div> <div class="MsoNormal" style="text-align: justify;"> <o:p></o:p></div> <div class="MsoNormal" style="text-align: justify;"> <br /></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg15GBGtX75y8RVry1QvcuBuGiqer1vl7QnBUKoCLTAeeQ4qsb1zHAX2e8CkTQYq5GSvc-HBqeMUAmwqj4Ja_bNw4109B_4cxso_9IA74QKvfTT7jCA9nnBnNdhbucNp03vejcpp9Me3JQ/s1600/multiway.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="382" data-original-width="696" height="218" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg15GBGtX75y8RVry1QvcuBuGiqer1vl7QnBUKoCLTAeeQ4qsb1zHAX2e8CkTQYq5GSvc-HBqeMUAmwqj4Ja_bNw4109B_4cxso_9IA74QKvfTT7jCA9nnBnNdhbucNp03vejcpp9Me3JQ/s400/multiway.PNG" width="400" /></a></div> <div class="MsoNormal" style="text-align: justify;"> <br /></div> <div class="MsoNormal" style="text-align: justify;"> This is the end of conditional construct in python and before we can get to python iterations let’s discuss about how to handle dangerous sections of code that raises an error that can be maskable i.e. for which we can write a piece of code that acts when a set of statements causes a traceback and tries to solve or bring the program out of the troubleshoot problem else the program can terminate if not handled. This is possible in python by use of the try/except structure. You surround a dangerous section of code with try and except. If the code in the try works - the except is skipped. If the code in the try fails - it jumps to the except section.<o:p></o:p></div> <div> <br /></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbuc3wIMWqz_lj6qqM8asp2UwVIgvbd_r08WiBy5-J0rMHYpJVAWRjnL5REPBi1VwEiP1Y9QWCHoWm-lQNCjMYlS_-PsICu1ptp9ONat-4LCsCDY-kbSjYTb1QI7WzLdl9DBGloSDXDlI/s1600/try_except.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="427" data-original-width="767" height="222" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbuc3wIMWqz_lj6qqM8asp2UwVIgvbd_r08WiBy5-J0rMHYpJVAWRjnL5REPBi1VwEiP1Y9QWCHoWm-lQNCjMYlS_-PsICu1ptp9ONat-4LCsCDY-kbSjYTb1QI7WzLdl9DBGloSDXDlI/s400/try_except.PNG" width="400" /></a></div> <div style="margin-left: 1em; margin-right: 1em; text-align: right;"> </div> <div class="MsoNormal" style="text-align: justify;"> <br /></div> <div class="MsoNormal" style="text-align: justify;"> Now let’s understand python iterations which is last topic of this post. What are iterations?? <span style="background: white; color: #222222;">They’re repetition of a set of statements. They can be categorized into two kinds – definite and indefinite.<o:p></o:p></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="background: white; color: #222222;"><br /></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="background: white; color: #222222;">While loops are called “indefinite loops” because they keep going until a logical condition becomes false. Sometimes it is a little harder to be sure if a loop of such a kind will terminate or not. A while loop is written in a following manner, its identified by the reserved word while and follows with a condition that evaluates to a Boolean value and only if it’s true that the control flow enter the loop body and hence the while loop is also called entry controlled loop.<o:p></o:p></span></div> <div class="MsoNormal" style="text-align: justify;"> <br /></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhSRaX44XGkYi5yfyqPZW6ExiWEJOpkFMBJqA0TVyv6wbF10r7Yy1EyAuLiEyGc8z4H_LuENmAHGAceZzJarehZ7_5OdFmGq_PJ5pJyZHpusS6bDEV5Wgw79MUJ4_597PhkvQ8PpAIwCy4/s1600/while.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="404" data-original-width="798" height="202" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhSRaX44XGkYi5yfyqPZW6ExiWEJOpkFMBJqA0TVyv6wbF10r7Yy1EyAuLiEyGc8z4H_LuENmAHGAceZzJarehZ7_5OdFmGq_PJ5pJyZHpusS6bDEV5Wgw79MUJ4_597PhkvQ8PpAIwCy4/s400/while.PNG" width="400" /></a></div> <div class="MsoNormal" style="text-align: right;"> </div> <div class="MsoNormal" style="text-align: justify;"> <span style="background: white; color: #222222;"><br /></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="background: white; color: #222222;">For loops are called “definite loops” because they execute the loop body for exact number of times. We can write a loop to run the loop once for each of the items in a set using the Python for construct. </span><span style="background-color: white; color: #222222;">Definite loops (for loops) have explicit iteration variables that change each time through a loop.</span><span style="background-color: white; color: #222222;">  </span><span style="background-color: white; color: #222222;">These iteration variables move through the sequence or set. The iteration variable “iterates” through the sequence (ordered set). The block (body) of code is executed once for each value in the sequence. The iteration variable moves through all of the values in the sequence.</span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="background-color: white; color: #222222;"><br /></span></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgSstnbzL2jbpfpJjNOHnDVutwqQb6x7XrOflEG6KAp0ckYcHtiYkCdTr45koInZnBlOBUa0a_ULOIB0-NS3tXfKaU3juQ3aFNfJul_5J1imwU_ptUoC75bkGcK53RYSJraqu9nj4FXeLY/s1600/for.PNG" imageanchor="1" style="background-color: white; margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="200" data-original-width="811" height="97" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgSstnbzL2jbpfpJjNOHnDVutwqQb6x7XrOflEG6KAp0ckYcHtiYkCdTr45koInZnBlOBUa0a_ULOIB0-NS3tXfKaU3juQ3aFNfJul_5J1imwU_ptUoC75bkGcK53RYSJraqu9nj4FXeLY/s400/for.PNG" width="400" /></a></div> <div class="MsoNormal" style="text-align: left;"> </div> <div class="MsoNormal" style="text-align: justify;"> <span style="background: white; color: #222222;"><br /></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="background: white; color: #222222;">The “is” and “is not” operators in python that are used in logical expression. The “is” operator implies is the same as but have more weight than the logical operator “==”. The “is not” operator logically is opposite of the “is” operator.<o:p></o:p></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="background: white; color: #222222;"><br /></span></div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEioTjgMDrCPiS4TbedK-HsoPKoXuhV6hjpvD6_EoRRls_EIgjqK0q96HIh2lztXMI7ld7IqNVg4-K0FFrIlWUcUxtj1CbZVlKC4xMs3xYDtH-pYdWULtjpp4nFC3uaXTCQsgdjF-n8YcWw/s1600/is.PNG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="247" data-original-width="420" height="188" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEioTjgMDrCPiS4TbedK-HsoPKoXuhV6hjpvD6_EoRRls_EIgjqK0q96HIh2lztXMI7ld7IqNVg4-K0FFrIlWUcUxtj1CbZVlKC4xMs3xYDtH-pYdWULtjpp4nFC3uaXTCQsgdjF-n8YcWw/s320/is.PNG" width="320" /></a></div> <o:p></o:p><br /> <div class="MsoNormal" style="text-align: justify;"> <span style="background: white; color: #222222;"><br /></span></div> <div class="MsoNormal" style="text-align: justify;"> <span style="background: white; color: #222222;">So here we are, at the end of the post, let’s summarise the topics we have seen today. (……..) This concludes the post, stay tuned for the next post on the topic of functions and string operations, until then guys enjoy your time browsing through other posts in the blog!!</span><span style="text-align: left;"> </span></div> <br /> <div class="separator" style="clear: both; text-align: center;"> <br /></div> </div>

Tutorials Learn Python from Scratch - Conditional Execution

Ola pythonista's, so this is a follow up of the previous post which was on the introduction of python. Here, I’m going to talk abou...

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Learn Python from Scratch - Introduction

<div dir="ltr" style="text-align: left;" trbidi="on"> <div class="MsoNormal"> <span lang="EN-US">Python is the language of the Python Interpreter and those who can converse with it. An individual who can speak Python is known as a Pythonista. It is a very uncommon skill, and nearly all known <b>Pythonistas </b>use software initially developed by Guido van Rossum.</span><o:p></o:p><br /> <span lang="EN-US"><br /></span></div> <div class="MsoNormal"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZGbHiLOqYS25LdDLOfaGasv1H-BaeIv5aiL46TKAw4-nNeuNMO82Xhx9-GHvfwdNC6uZ1IESPTLWVWJtcPQZm3p9me6ag-vyF1qkjombexuooYuGmVRcJU-mSf3KYRFQOdpGUbId3XGg/s1600/chevron.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" data-original-height="275" data-original-width="761" height="143" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZGbHiLOqYS25LdDLOfaGasv1H-BaeIv5aiL46TKAw4-nNeuNMO82Xhx9-GHvfwdNC6uZ1IESPTLWVWJtcPQZm3p9me6ag-vyF1qkjombexuooYuGmVRcJU-mSf3KYRFQOdpGUbId3XGg/s400/chevron.jpg" width="400" /></a></div> <div class="MsoNormal"> When we are at the python interpreter, it displays chevron prompt (>>>) on the terminal, where it is asking you <b>“What’s next??”.</b></div> <div class="MsoNormal"> <o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> <b><br /></b> <b><br /></b> <b><br /></b> <div style="text-align: left;"> <b><br /></b></div> <div style="text-align: left;"> <b>How do we speak the language of python??</b><o:p></o:p></div> </div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> This must be the question on most of your minds when trying to learn the language initially. Just like the English Language, we will first start of by learning words, sentences and then paragraphs in python.<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbqrH36G51V1wdlubB4rLMVK-UOwb5Sm-97rXkeIeAWItPY1bdil_g1BWIulw4GvsiIReEBxGpFZFPVQuRaPBvYjDs-sGPYJcTsxY4tdaGiFlfIyy4xmk5nSEb7jopDjv-cmEn6ZBe1FE/s1600/reserved-words.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em; text-align: center;"><img border="0" data-original-height="197" data-original-width="481" height="162" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbqrH36G51V1wdlubB4rLMVK-UOwb5Sm-97rXkeIeAWItPY1bdil_g1BWIulw4GvsiIReEBxGpFZFPVQuRaPBvYjDs-sGPYJcTsxY4tdaGiFlfIyy4xmk5nSEb7jopDjv-cmEn6ZBe1FE/s400/reserved-words.jpg" width="400" /></a><b>Reserved Words:</b> They’re words that are predefined in the python library and have some meaning. These words cannot be used as variables or as a matter of fact to do anything that these words don’t offer. Some of these reserved words that we would come across are stated in the figure alongside.<o:p></o:p><br /> <br /></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> </div> <div class="MsoNormal"> Constants and variables are other literals that are supported by python. “<b>Constants</b>”, as the word suggests <span lang="EN-US">they’re fixed values such as numbers, letters, and strings, where their value does not change</span> throughout the scope of the program. <span lang="EN-US">A <b>variable </b>is a named place in the memory where a programmer can store data and later retrieve the data using the variable “name”</span>.<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> Since we programmers are given a choice in how we choose our variable names, there is a bit of “best practice”, we name variables to help us remember what we intend to store in them (“mnemonic” = “memory aid”). This can confuse beginning students because well-named variables often “sound” so good that they must be keywords. There are rules that have to be followed while naming a variable so as to reduce ambiguity for the interpreter, and they’re:</div> <div class="MsoNormal"> </div> <ol style="text-align: left;"> <li> <span style="text-indent: -18pt;">Must start with a letter or underscore _</span></li> <li>Must consist of letters, numbers, and underscores</li> <li>Case Sensitive</li> <li>Cannot be Reserved Word.</li> </ol> <br /> <div class="MsoListParagraphCxSpMiddle" style="mso-list: l1 level1 lfo1; text-indent: -18.0pt;"> <o:p></o:p></div> <div class="MsoListParagraphCxSpLast"> <br /></div> <div class="MsoNormal"> Next comes sentences, or here we are specifically talking about how do we code instruction in python. For simpler understanding let’s start off with arithmetic expressions.<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal">                 Assignment Statement: x=2<o:p></o:p></div> <div class="MsoNormal">                 Arithmetic assignment: x=x+2<o:p></o:p></div> <div class="MsoNormal">                 Output Statement: print(x)<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> So, what all did we come across in the previous three instructions, operators, constants, variables and function.<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> Numeric Expressions that are used in python are mentioned below, //pic of operator operation table <o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> When we have so many operators for numeric expressions to perform simple calculation, there must be a way python must know which of them to do first, so to address this situation we will have to learn about the concept of operator precedence, i.e. which operator takes precedence over the others.<o:p></o:p></div> <div class="MsoNormal"> <span lang="EN-US"><br /></span></div> <div class="MsoNormal"> <span lang="EN-US">Highest precedence rule to lowest precedence rule:<o:p></o:p></span></div> <div class="MsoListParagraphCxSpFirst" style="text-align: left; text-indent: -18pt;"> </div> <ol style="text-align: left;"> <li>Parentheses are always respected</li> <li>Exponentiation (raise to a power)</li> <li>Multiplication, Division, and Remainder</li> <li>Addition and Subtraction</li> <li>Left to right</li> </ol> <o:p></o:p><br /> <div class="MsoNormal"> Note: Remember in python3 when you perform integer division it produces a floating-point result.</div> <div class="MsoNormal"> <o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> Now lastly let’s see how to write paragraphs, Interactive python is good for experimenting programs of 3 to 4 lines, but most programs are much longer than that, so we type our python scripts in a file using an editor and then we tell python to run those commands that we have coded in the file. As a convention we add .py extension for python files. <o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> <b>Sequential flow of execution</b> is followed by python interpreter unless it comes across some branching, looping or conditional statement. This means to say that when a program is running, that the flow of execution occurs from one step to the next. As programmers we set paths for the program to follow.<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiF_ENyI8hwXYX60oqY_aeYcBvrND5VJXOJn4sHv9ElnSCWwdLq0hoxqbZnUlh0ih6edFrKVxY7O_Dl03ulZeg7p8fk6NsXmkh2Uzhu5XN_gRIF_8WAQTpjtIRIwL2ZXQECxx9pDcbIZQ4/s1600/type.jpg" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="320" data-original-width="400" height="256" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiF_ENyI8hwXYX60oqY_aeYcBvrND5VJXOJn4sHv9ElnSCWwdLq0hoxqbZnUlh0ih6edFrKVxY7O_Dl03ulZeg7p8fk6NsXmkh2Uzhu5XN_gRIF_8WAQTpjtIRIwL2ZXQECxx9pDcbIZQ4/s320/type.jpg" width="320" /></a>In python the variables are not declared by the programmer and the python interpreter resolves this during the interpretation time of the program and hence the language is dynamic. Python knows what type everything is, but some operators are prohibited as in you cannot add a numeric 1 to a string. We can ask python what type some named space is by using the built-in function, type().<o:p></o:p></div> <div class="MsoNormal"> </div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> There are certain scenario when the programmer would explicitly like to typecast a named space and to do so there are some built-in functions available to us, such as:<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> <div style="text-align: right;"> </div> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhXhSs8QKi33-XLraXLvR6I1gN6NN3mby9zFdWIarL44AdPL0A_nDKssFdkz-6OZPcHNjeKOg5yk8mgGUrl4gopGUMaE9iIHHOssP_hw2Ub72EeP37aGEzBVd6eZU7peGZu8gbwibZW7P0/s1600/typecasting.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img border="0" data-original-height="261" data-original-width="596" height="175" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhXhSs8QKi33-XLraXLvR6I1gN6NN3mby9zFdWIarL44AdPL0A_nDKssFdkz-6OZPcHNjeKOg5yk8mgGUrl4gopGUMaE9iIHHOssP_hw2Ub72EeP37aGEzBVd6eZU7peGZu8gbwibZW7P0/s400/typecasting.jpg" width="400" /></a></div> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgkQnxEAjoK1MwBJAmFdCYunpmQwec5PSHobjUE4Qzf0HiQspOyta_FCEM9i8tLlwXK_NLIMtBEEYFLCDWGSVmzUinEVlNyPLz351m1dFs51ityVefMf1djL6D-L2o3wpncpzfrjZMj26E/s1600/input.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em; text-align: center;"><img border="0" data-original-height="104" data-original-width="380" height="87" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgkQnxEAjoK1MwBJAmFdCYunpmQwec5PSHobjUE4Qzf0HiQspOyta_FCEM9i8tLlwXK_NLIMtBEEYFLCDWGSVmzUinEVlNyPLz351m1dFs51ityVefMf1djL6D-L2o3wpncpzfrjZMj26E/s320/input.jpg" width="320" /></a>For python script to be interactive it must take input from the user and it does that by invoking a function, input() which takes a string argument and returns a string object containing the value entered by the user. The same operation is done by function raw_input() in python2.<o:p></o:p></div> <div class="MsoNormal"> </div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> Let’s say we want to read a number from the user then we must convert the string object to integer or float using the typecasting function which we have seen earlier.<o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> <div class="separator" style="clear: both; text-align: center;"> <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmcPeQNxXihiQYDvcWURGCi__YRwEidGC5b6u0YWDJoiOM5FbtBwADuUx7Gas3lVcxU3SepJ85VrNXhlvz-hAe7elQIyikwJz9w2QgmuAj7JUmn1fcV9pJ1OBurHFDus6_Ks_JfrLWkoI/s1600/input_convert.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="250" data-original-width="314" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmcPeQNxXihiQYDvcWURGCi__YRwEidGC5b6u0YWDJoiOM5FbtBwADuUx7Gas3lVcxU3SepJ85VrNXhlvz-hAe7elQIyikwJz9w2QgmuAj7JUmn1fcV9pJ1OBurHFDus6_Ks_JfrLWkoI/s1600/input_convert.jpg" /></a></div> <br /></div> <div class="MsoNormal"> <b>Comments </b>in python are prefixed by the ‘#’ symbol, when the interpreter comes across a line prefixed with ‘#’ then it doesn’t execute it or ignores it as comment. As a beginner in programming you might think why do we need to write comments in a program, the reasons are,<o:p></o:p></div> <div class="MsoNormal"> <span lang="EN-US"> -  Describe what is going to happen in a sequence of code</span><o:p></o:p></div> <div class="MsoNormal"> <span lang="EN-US"> -  Document who wrote the code or other ancillary information</span><o:p></o:p></div> <div class="MsoNormal"> <span lang="EN-US"> -  Turn off a line of code - perhaps temporarily</span><o:p></o:p></div> <div class="MsoNormal"> <br /></div> <div class="MsoNormal"> So now we have come to the end of introduction in python, and at this checkpoint we have pictured the edges of a big canvas about python and we will focus on the details of this canvas in the next post. Stay tuned for the next post on the topic of conditional statements and iterations, until then guys enjoy your time browsing through other posts in the blog!!<br /> <br /> <br /> <br /> <div class="separator" style="clear: both; text-align: center;"> <br /></div> <br /> <div class="separator" style="clear: both; text-align: center;"> <br /></div> <br /> <div class="separator" style="clear: both; text-align: center;"> <br /></div> <o:p></o:p></div> </div>

Tutorials Learn Python from Scratch - Introduction

Python is the language of the Python Interpreter and those who can converse with it. An individual who can speak Python is known as a Pyth...

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