Perl

Things that do work

Print out the contents of $variable in a structured format.

use Data::Dumper;
print Dumper($variable);

if-then-else:

if < expr > {
 <codeblock>
} elsif < expr ) {
 <codeblock>
} else {
 <codeblock>
}
print Dumper($variable);

$var += <value>

Add <value> to $var (works for -, *, / too)

$string .= $addstring

Concatenate $string and $addstring

$string =~ s/<regexp>/<newvalue>/[g]

Substitute <regexp> with <newvalue> in $string. The g modifier makes the all occurrences of <regexp> are substituted.

$newstring = substr($string,start,length)

Return substring of $string

sprintf(format,$string)

Return formatted string. format is e.g. "%.3f". Check Python:Strings#Advanced for all formats.

Searching is explained in Regular Expressions.