#!/usr/bin/env perl

use strict;
use warnings;

my $text;
my $match = 0;
my $regex = qr/int\s+main\s*\(/;

{
    local $/;                       # enable "slurp" mode
    $text = <DATA>;                  # read whole file
}

while ($text =~ /$regex/gms)
{
    print "Match found on line ",
            scalar ( split /\n/, substr $text, 0, pos($text) )
                - scalar ( split /\n/, ${^MATCH} ) + 1,
            "\n";
    $match = 1;
}

print "No matches found\n" unless $match;

__DATA__
/* Dummy multi-main C code */

int
main(int argc, char** argv)

int main(int argc, char** argv)

/* END */