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Last Updated : 21 Feb, 2019

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Perl | Basic Syntax of a Perl Program Perl is a general purpose, high level interpreted and dynamic programming language. Perl was originally developed for the text processing like extracting the required information from a specified text file and for converting the text file into a different form. Perl supports both the procedural and Object-Oriented programming. Perl is a lot similar 10 min read Perl | chomp() Function The chomp() function in Perl is used to remove the last trailing newline from the input string. Syntax: chomp(String) Parameters: String : Input String whose trailing newline is to be removed Returns: the total number of trailing newlines removed from all its arguments Example 1: C/C++ Code #!/usr/bin/perl # Initialising a string $string = &quo 2 min read Perl | chop() Function The chop() function in Perl is used to remove the last character from the input string. Syntax: chop(String) Parameters: String : It is the input string whose last characters are removed. Returns: the last removed character. Example 1: #!/usr/bin/perl # Initialising a string $string = "GfG is a computer science portal"; # Calling the chop 1 min read Perl | rename() Function rename() function in Perl renames the old name of a file to a new name as given by the user. Syntax: rename(old_file_path, new_file_path) Parameters: old_file_path: path of the old file along with its name new_file_path: path of the new file along with its name Returns 0 on failure and 1 on success Example: #!/usr/bin/perl -w # Calling the rename() 1 min read Perl | cos() Function This function is used to calculate cosine of a VALUE or $_ if VALUE is omitted. The VALUE should be expressed in radians. Syntax: cos(VALUE) Parameters: VALUE in the form of radians Returns: Function returns cosine of VALUE. Example 1: #!/usr/bin/perl # Calling cos function $var = cos(5); # Printing value of cos(5) print "cos value of 5 is $va 1 min read Perl | sin() Function This function is used to calculate sine of a VALUE or $_ if VALUE is omitted. This function always returns a floating point. Syntax: sin(VALUE) Parameters: VALUE in the form of float Returns: Function returns sine of VALUE. Example 1: #!/usr/bin/perl # Calling sin() function $var = sin(5); # Printing value for sin(5) print "sin value of 5 is $ 1 min read Perl | abs() function This function returns the absolute value of its argument. If a pure integer value is passed then it will return it as it is, but if a string is passed then it will return zero. If VALUE is omitted then it uses $_ Syntax: abs(VALUE) Parameter: VALUE: It is a required number which can be either positive or negative or a string. Returns: Function retu 2 min read Perl | atan2() Function This function is used to calculate arctangent of Y/X in the range -PI to PI. Syntax: atan2(Y, X) Parameters: Y and X which are axis values Returns: Function returns arctangent of Y/X in the range -PI to PI. Example1: #!/usr/bin/perl # Assigning values to X and y $Y = 45; $X = 70; # Calling atan2() function $return_val = atan2($Y, $X); # printing th 1 min read Perl | splice() - The Versatile Function In Perl, the splice() function is used to remove and return a certain number of elements from an array. A list of elements can be inserted in place of the removed elements. Syntax: splice(@array, offset, length, replacement_list) Parameters: @array - The array in consideration. offset - Offset of removal of elements. length - Number of elements to 9 min read Perl | delete() Function Delete() in Perl is used to delete the specified keys and their associated values from a hash, or the specified elements in the case of an array. This operation works only on individual elements or slices. Syntax: delete(LIST) Parameters: LIST which is to be deleted Returns: undef if the key does not exist otherwise it returns the value associated 1 min read Perl | each() Function This function returns a Two-element list consisting of the key and value pair for the next element of a hash when called in List context, so that you can iterate over it. Whereas it returns only the key for the next element of the hash when called in scalar context. Syntax: each MY_HASH Parameter: MY_HASH is passed as a parameter to this function R 1 min read Perl | index() Function This function returns the position of the first occurrence of given substring (or pattern) in a string (or text). We can specify start position. By default, it searches from the beginning(i.e. from index zero). Syntax: # Searches pat in text from given index index(text, pat, index) # Searches pat in text index(text, pat) Parameters: text: String in 3 min read Perl | int() function int() function in Perl returns the integer part of given value. It returns $_ if no value provided. Note that $_ is default input which is 0 in this case. The int() function does not do rounding. For rounding up a value to an integer, sprintf is used. Syntax: int(VAR) Parameters: VAR: value which is to be converted into integer Returns: Returns the 1 min read Perl | join() Function join() function in Perl combines the elements of LIST into a single string using the value of VAR to separate each element. It is effectively the opposite of split. Note that VAR is only placed between pairs of elements in the LIST; it will not be placed either before the first element or after the last element of the string. Supply an empty string 1 min read Perl | keys() Function keys() function in Perl returns all the keys of the HASH as a list. Order of elements in the List need not to be same always, but, it matches to the order returned by values and each function. Syntax: keys(HASH) Parameter: HASH: Hash whose keys are to be printed Return: For scalar context, it returns the number of keys in the hash whereas for List 1 min read Perl | lc() Function for Lower Case Conversion lc() function in Perl returns a lowercased version of VAR, or $_ if VAR is omitted. Syntax: lc(VAR)Parameter: VAR: Sentence which is to be converted to lower caseReturn: Lowercased version of VAR, or $_ if VAR is omitted Example 1: C/C++ Code #!/usr/bin/perl # Original String containing both # lower and upper case letters $original_string = "G 1 min read Perl | lcfirst() Function lcfirst() function in Perl returns the string VAR or $_ after converting the First character to lowercase. Syntax: lcfirst(VAR) Parameter: VAR: Sentence whose first character is to be converted to lower case Returns: the string VAR or $_ with the first character lowercased Example 1: #!/usr/bin/perl # Original String containing both # lower and upp 1 min read Perl | length() Function length() function in Perl finds length (number of characters) of a given string, or $_ if not specified. Syntax:length(VAR) Parameter: VAR: String or a group of strings whose length is to be calculated Return: Returns the size of the string. Example 1: #!/usr/bin/perl # String whose length is to be calculated $orignal_string = "Geeks for Geeks 1 min read Perl | substr() function substr() in Perl returns a substring out of the string passed to the function starting from a given index up to the length specified. This function by default returns the remaining part of the string starting from the given index if the length is not specified. A replacement string can also be passed to the substr() function if you want to replace 2 min read Perl | oct() Function oct() function in Perl converts the octal value passed to its respective decimal value. For example, oct('1015') will return '525'. This function returns the resultant decimal value in the form of a string which can be used as a number because Perl automatically converts a string to a number in numeric contexts. If the passed parameter is not an oc 1 min read Perl | log() Function log() function in Perl returns the natural logarithm of value passed to it. Returns $_ if called without passing a value. log() function can be used to find the log of any base by using the formula: Syntax: log(value) Parameter: value: Number of which log is to be calculated Returns: Floating point number in scalar context Example 1: #!/usr/bin/per 2 min read Perl | push() Function push() function in Perl is used to push a list of values onto the end of the array. push() function is often used with pop to implement stacks. push() function doesn't depend on the type of values passed as list. These values can be alpha-numeric. Syntax: push(Array, List) Parameter: Array: in which list of values is to be added List: which is to b 1 min read Perl | rand() Function rand() function in Perl returns a random fractional number between 0 and the positive number value passed to it, or 1 if no value is specified. Automatically calls srand() to seed the random number generator unless it has already been called. Syntax: rand(range_value) Parameter: range_value: a positive number to specify the range Returns: a random 1 min read Perl | prototype() Function prototype() function in Perl returns a string containing the prototype of the function or reference passed to it as an argument, or undef if the function has no prototype. Syntax: prototype(function_name) Parameter: function_name: Function whose prototype is to be determined Returns: prototype of the function passed or undef if no prototype exists 1 min read Perl | reset() Function reset() function in Perl resets (clears) all package variables starting with the letter range specified by value passed to it. Generally it is used only within a continue block or at the end of a loop. Note: Use of reset() function is limited to variables which are not defined using my() function. Syntax: reset(letter_range) Parameter: letter_range 2 min read Perl | quotemeta() Function quotemeta() function in Perl escapes all meta-characters in the value passed to it as parameter. Example: Input : "GF*..G" Output : "GF\*\.\.G" Syntax: quotemeta(value) Parameter: value: String containing meta-characters Return: a string with all meta-characters escaped Example 1: #!/usr/bin/perl -w $string = "GF*\n[.]*G"; print "Ori 1 min read Perl | Array pop() Function pop() function in Perl returns the last element of Array passed to it as an argument, removing that value from the array. Note that the value passed to it must explicitly be an array, not a list. Syntax: pop(Array) Returns: undef if list is empty else last element from the array. Example 1: #!/usr/bin/perl -w # Defining an array of integers @array 1 min read Perl | return() Function return() function in Perl returns Value at the end of a subroutine, block, or do function. Returned value might be scalar, array, or a hash according to the selected context. Syntax: return Value Returns: a List in Scalar Context Note: If no value is passed to the return function then it returns an empty list in the list context, undef in the scala 2 min read Perl | reverse() Function reverse() function in Perl when used in a list context, changes the order of the elements in the List and returns the List in reverse order. While in a scalar context, returns a concatenated string of the values of the List, with each character of the string in the opposite order. Syntax: reverse List Returns: String in Scalar Context and List in L 1 min read Perl | rindex() Function rindex() function in Perl operates similar to index() function, except it returns the position of the last occurrence of the substring (or pattern) in the string (or text). If the position is specified, returns the last occurrence at or before that position. Syntax: # Searches pat in text from given Position rindex text, pattern, Position # Searche 2 min read

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'); $('.spinner-loading-overlay').show(); jQuery.ajax({ url: writeApiUrl + 'create-improvement-post/?v=1', type: "POST", contentType: 'application/json; charset=utf-8', dataType: 'json', xhrFields: { withCredentials: true }, data: JSON.stringify({ gfg_id: post_id, }), success:function(result) { $('.spinner-loading-overlay:eq(0)').remove(); $('.improve-modal--overlay').hide(); $('.unlocked-status--improve-modal-content').css("display","none"); $('.create-improvement-redirection-to-write').attr('href',writeUrl + 'improve-post/' + `${result.id}` + '/', '_blank'); $('.create-improvement-redirection-to-write')[0].click(); }, error:function(e) { $('.spinner-loading-overlay:eq(0)').remove(); var result = e.responseJSON; if(result.detail.non_field_errors.length){ $('.improve-modal--improve-content .improve-modal--improve-content-modified').text(`${result.detail.non_field_errors}.`); jQuery('.improve-modal--overlay').show(); jQuery('.improve-modal--improvement').show(); $('.locked-status--impove-modal').css("display","block"); $('.unlocked-status--improve-modal-content').css("display","none"); $('.improve-modal--improvement').attr("status","locked"); $('.improvement-reason-modal').hide(); } }, }); return; } var improvement_reason_html = ""; for(var comment of commentArray) { // loop creating improvement reason list markup var comment_id = comment['id']; var comment_text = comment['suggestion']; improvement_reason_html += `

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`; } $('.improvement-reasons_wrapper').html(improvement_reason_html); $('.improvement-bottom-btn').html("Create Improvement"); $('.improve-modal--improvement').hide(); $('.improvement-reason-modal').show(); }, error: function(e){ $('.spinner-loading-overlay:eq(0)').remove(); // stop loader when ajax failed; }, }); }, error:function(e) { $('.spinner-loading-overlay:eq(0)').remove(); var result = e.responseJSON; if(result.detail.non_field_errors.length){ $('.improve-modal--improve-content .improve-modal--improve-content-modified').text(`${result.detail.non_field_errors}.`); jQuery('.improve-modal--overlay').show(); jQuery('.improve-modal--improvement').show(); $('.locked-status--impove-modal').css("display","block"); $('.unlocked-status--improve-modal-content').css("display","none"); $('.improve-modal--improvement').attr("status","locked"); $('.improvement-reason-modal').hide(); } }, }); } else { if(loginData && !loginData.isLoggedIn) { $('.improve-modal--overlay').hide(); if ($('.header-main__wrapper').find('.header-main__signup.login-modal-btn').length) { $('.header-main__wrapper').find('.header-main__signup.login-modal-btn').click(); } return; } } }); $('.left-arrow-icon_wrapper').on('click',function(){ if($('.improve-modal--suggestion').is(":visible")) $('.improve-modal--suggestion').hide(); else{ $('.improvement-reason-modal').hide(); } $('.improve-modal--improvement').show(); }); function loadScript(src, callback) { var script = document.createElement('script'); script.src = src; script.onload = callback; document.head.appendChild(script); } function suggestionCall() { var suggest_val = $.trim($("#suggestion-section-textarea").val()); var array_String= suggest_val.split(" ") var gCaptchaToken = $("#g-recaptcha-response-suggestion-form").val(); var error_msg = false; if(suggest_val != "" && array_String.length >=4){ if(suggest_val.length <= 2000){ var payload = { "gfg_post_id" : `${post_id}`, "suggestion" : `

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`, } if(!loginData || !loginData.isLoggedIn) // User is not logged in payload["g-recaptcha-token"] = gCaptchaToken jQuery.ajax({ type:'post', url: "https://apiwrite.geeksforgeeks.org/suggestions/auth/create/", xhrFields: { withCredentials: true }, crossDomain: true, contentType:'application/json', data: JSON.stringify(payload), success:function(data) { jQuery('.spinner-loading-overlay:eq(0)').remove(); jQuery('#suggestion-section-textarea').val(""); jQuery('.suggest-bottom-btn').css("display","none"); // Update the modal content const modalSection = document.querySelector('.suggestion-modal-section'); modalSection.innerHTML = `

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`; }, error:function(data) { jQuery('.spinner-loading-overlay:eq(0)').remove(); jQuery('#suggestion-modal-alert').html("Something went wrong."); jQuery('#suggestion-modal-alert').show(); error_msg = true; } }); } else{ jQuery('.spinner-loading-overlay:eq(0)').remove(); jQuery('#suggestion-modal-alert').html("Minimum 5 Words and Maximum Character limit is 2000."); jQuery('#suggestion-modal-alert').show(); jQuery('#suggestion-section-textarea').focus(); error_msg = true; } } else{ jQuery('.spinner-loading-overlay:eq(0)').remove(); jQuery('#suggestion-modal-alert').html("Enter atleast four words !"); jQuery('#suggestion-modal-alert').show(); jQuery('#suggestion-section-textarea').focus(); error_msg = true; } if(error_msg){ setTimeout(() => { jQuery('#suggestion-section-textarea').focus(); jQuery('#suggestion-modal-alert').hide(); }, 3000); } } document.querySelector('.suggest-bottom-btn').addEventListener('click', function(){ jQuery('body').append('

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