Perl: How to include variables in a regular expression

[ATC]

Now and then you want to include a variable string in a regular expression like this:

"if (/\w{1,4}$var_(\d*)/)"

Unfortunately, this will confuse the compiler, because it can't decide exactly what the variable name is, and incorrectly try to use "$var_". But the variable you wanted to use was "$var".

[ATC]

By using the escape codes \Q and \E you can tell the compiler where the variable name begins and ends.

Example:
"if (/\w{1,4}\Q$var\E_(\d*)/) "

Thanks to Savuud for this one!! :-)