Question

Please do pardon me if my question sounds a bit awkward. I am looking for a regex which will replace line numbers in perl source file without affecting values assigned to scalars.

I think below will make my question a little bit clearer. Say I have a perl source which looks like this:

1. $foo = 2.4;
2. print $foo;

I would like a regular expression to replace those line numbers (1. 2. etc..) without affecting value assigned to scalars, and so in this case $foo.

Thanks

Answer 1

Within a perl regex you can use the caret symbol ^ to represent the start of a line. $ represents the end of a line. These are known as anchors.

So to find a number \d at the beginning of a line (only) you can search for

/^\d+/

If you wanted to remove those numbers you can “replace” them with nothing, as in

s/^\d+//g

You also want to include the dot after the number, so you might try
;

/^\d+./

But in regex a dot represents “any character” so you will need to escape the dot to have it interpreted literally

/^\d+\./

The caret symbol ^ also serves double-duty in character sets (it negates them), I only mention this as it is a common source of confusion when learning regex.

/[^\d]/   # Match characters that are not digits