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Articles on Trending Technologies
Technical articles with clear explanations and examples
The carp Function in Perl
The carp function in Perl is the basic equivalent of warn and prints the message to STDERR without actually exiting the script and printing the script name.package T; require Exporter; @ISA = qw/Exporter/; @EXPORT = qw/function/; use Carp; sub function { carp "Error in module!"; } 1;When called from a script like below −use T; function();It will produce the following result −Error in module! at test.pl line 4
Read MoreErrors within Perl Modules
There are two different situations we should be able to handle while using Perl Programming −Reporting an error in a module that quotes the module's filename and line number - this is useful when debugging a module, or when you specifically want to raise a module-related, rather than script-related, error.Reporting an error within a module that quotes the caller's information so that you can debug the line within the script that caused the error. Errors raised in this fashion are useful to the end-user, because they highlight the error in relation to the calling script's origination line.The warn and die ...
Read MoreThe unless & die Function in Perl
The unless function in Perl is the logical opposite to if: statements can completely bypass the success status and only be executed if the expression returns false. For example −unless(chdir("/etc")) { die "Error: Can't change directory - $!"; }The unless statement is best used when you want to raise an error or alternative only if the expression fails. The statement also makes sense when used in a single-line statement −die "Error: Can't change directory!: $!" unless(chdir("/etc"));Here we die only if the chdir operation fails.The die FunctionThe die function works just like warn, except that it also calls exit. Within ...
Read MoreCreate, Delete and Change Directories in Perl
You can use mkdir function in Perl to create a new directory. You will need to have the required permission to create a directory.#!/usr/bin/perl $dir = "/tmp/perl"; # This creates perl directory in /tmp directory. mkdir( $dir ) or die "Couldn't create $dir directory, $!"; print "Directory created successfully";Remove a directoryYou can use rmdir function in Perl to remove a directory. You will need to have the required permission to remove a directory. Additionally this directory should be empty before you try to remove it.#!/usr/bin/perl $dir = "/tmp/perl"; # This removes perl directory from /tmp directory. rmdir( $dir ) or die "Couldn't ...
Read MoreDisplay all the Files in Perl
There are various ways to list down all the files available in a particular directory using Perl. First let's use the simple way to get and list down all the files using the glob operator −#!/usr/bin/perl # Display all the files in /tmp directory. $dir = "/tmp/*"; my @files = glob( $dir ); foreach (@files ) { print $_ . ""; } # Display all the C source files in /tmp directory. $dir = "/tmp/*.c"; @files = glob( $dir ); foreach (@files ) { print $_ . ""; } # Display all the hidden files. $dir = "/tmp/.*"; @files ...
Read MoreRemove vowels from a String in C++
The following C++ program illustrates how to remove the vowels (a, e, i, u, o) from a given string. In this context, we create a new string and process input string character by character, and if a vowel is found it is excluded in the new string, otherwise the character is added to the new string after the string ends we copy the new string into the original string. The algorithm is as follows;AlgorithmSTART Step-1: Input the string Step-3: Check vowel presence, if found return TRUE Step-4: Copy it to another array Step-5: Increment the counter ...
Read MoreReplacing words with asterisks in C++
This aim of this program to replace a particular word with asterisks in the string by using the c++ programming code. The essential function of vector and string class essay a key role to achieve the prospective results. The algorithm is as follows;AlgorithmSTART Step-1: Input string Step-2 Split the string into words and store in array list Step-3: Iterate the loop till the length and put the asterisk into a variable Step-4: Traverse the array foreah loop and compare the string with the replaced word Step-5: Print ENDNow, the following code is carved out based ...
Read MoreWrite a program for Happy Woman's Day in c++
The woman day which is celebrated on 7th October worldwide is carved into a c++ programming code as following;Example#include using namespace std; int main(){ // Initializing size of // design int n = 5; // Loop to print Circle // (Upper part of design) // Outer loop to // control height of // design for (int i = 0; i
Read MoreGetting File Information in Perl
You can test certain features very quickly within Perl using a series of test operators known collectively as -X tests. For example, to perform a quick test of the various permissions on a file, you might use a script like this −#/usr/bin/perl my $file = "/usr/test/file1.txt"; my (@description, $size); if (-e $file) { push @description, 'binary' if (-B _); push @description, 'a socket' if (-S _); push @description, 'a text file' if (-T _); push @description, 'a block special file' if (-b _); push @description, 'a character special file' if (-c _); push @description, ...
Read MorePositioning inside a File in Perl
You can use to tell function in Perl to know the current position of a file and seek function to point a particular position inside the file.Perl tell FunctionThe first requirement is to find your position within a file, which you do using the tell function −tell FILEHANDLE tellThis returns the position of the file pointer, in bytes, within FILEHANDLE if specified, or the current default selected filehandle if none is specified.Perl seek FunctionThe seek function positions the file pointer to the specified number of bytes within a file −seek FILEHANDLE, POSITION, WHENCEThe function uses the fseek system function, and you have ...
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