Perl Basics Cheatsheet Cheat Sheet

Arrays	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($x)	Length of a string
	chomp($line);	Remove a newline at the end of a string
	$short=substr ($long, 2, 5)	Characters 3-7 of $long (first char is 0!)
Hashes	@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)
	$x=<HANDLE>	Read a line from filehandle HANDLE, put in $x
	close(HANDLE);	Stop reading/writing a previously opened file
Exit	exit;	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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