Regular expressions - substring

smcelhinney

Guys

Am googling for the last couple of hours, no joy. Maybe someone can provide an epiphany.

I have this list of numbers in the format XXXXXX,XXXXXXXXXXXX, and I need to use regex to extract everything after the comma, to the end of the line.

Any thoughts?

Kai

I dont think reg ex is what your looking for. Reg ex looks for patterns but you cant really use it the way you want to.
What programming language are you using.
in c# you could return the last digits like this

private string ParseNumber(string numberToParse)
{
	int commaLocation = numberToparse.IndexOf(",");
	string returnValue ="";
	if(commaLocation > -1 & numberToParse.Length > commaLocation + 1)
	{
		returnValue = numberToParse.SubString(commaLocation +1);
	}
	return returnValue;
}

seamus

Most regexp functions provide a means by which you "tag" sections of the string which match the regexp, then you can extract those tagged bits.

The regexp may look something like this:
/^\d*,(\.*)$/
So the function will attempt to match the entire expression, but only return the bit in parentheses.

Tom Dunne

As an alternative, what string handling functions does the languages have?

Look for INSTR, LEN and SUBSTR.

INSTR is usually of the format INSTR(string, ',') and will return the location of the comma (in this case) within string. You now know where the comma is, so you look from this point to the end of the string for what you want.

It would be something like:

Newstring:= substr ( INSTR(string,','), LEN(string) )

CasimiR

You could also split the string on the ","
Depending on the language you re using : strtok , split, explode ...

eg in perl

$t = '123455,789012345678';
$a = (split(/,/, $t))[1];

daymobrew

seamus wrote:

The regexp may look something like this:
/^\d*,(\.*)$/
So the function will attempt to match the entire expression, but only return the bit in parentheses.

Here is an example of this in perl.

#!/usr/bin/perl -w

my $var = '123455,789012345678';
print $var, "\n";
# A substitution that discards what is before the comma.
$var =~ s/^\d+,//;
print $var, "\n";

$var = '123455,789012345678';
print $var, "\n";
# A match check that captures the numbers after the comma.
if ( $var =~ /^\d+,(\d+)$/ ) {
  $var = $1;
}
print $var, "\n";