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Perl Basics Cheatsheet Cheat Sheet by

Perl Basics cheatsheet from command line


push @arr, $x
Add to end of array
$x = pop @arr;
Remove last element of array, put in $x
shift @arr; (See also unshift)
Remove first element of an arrray, put in $x
$size = scalar @arr;
Number of things in the array
See also: split, join, splice, sort
split string­->a­rray, join array-­>st­ring, delete part of array, sort array in many ways
scalar variables
while (defined ($x=<>)) {code}
False if variable has never been set (or when you try to read past the end of an input file)
Length of a string
Remove a newline at the end of a string
$short­=substr ($long, 2, 5)
Characters 3-7 of $long (first char is 0!)
@key = keys %hash
The lookup terms in the hash
if (exists $hh{“H­sp”}) {...}
See whether hash %hh has a value for key Hsp
Input/­Output and Files
open(H­ANDLE, "­>ou­tfi­le") or die “Can’t open $outfile: $!\n”
Open outfile for writing, and associate it with filehandle HANDLE. Use “
print $x; print HANDLE $x;
Prints to standard output (screen), Print to filehandle HANDLE
warn “Something wrong\n”;
Prints to standard error (screen)
Read a line from filehandle HANDLE, put in $x
Stop readin­g/w­riting a previously opened file
Exits the program
die "­Som­ething broke!­\n";
exits the program with error message
>> Operators and Loops
>> Matching and Regular Expres­sions
Source :GreyCampus
Training & Certif­ication in Perl :Perl Certif­ication


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