Print diff between function a() and b() in foo.c file.

diff.pl

#!/usr/bin/env perl
#
# Last modified: Fri, 28 Dec 2012 15:37:46 +0900
#
# Usage: perl diff.pl foo.c func1 func2
#        will compare func1() and func2() in foo.c
#
# Note: The function must finish with "}" at the beggining of line, like:
#       int func(int a) {
#         ...
#       }  <== Here!

use strict;
use warnings;
use Text::Diff 'diff';

my $f1 = 0;
my $f2 = 0;
my $str1 = "";
my $str2 = "";

my $file = $ARGV[0];
my $name1 = $ARGV[1];
my $name2;

if (@ARGV < 3) {
  $name2 = $name1 . "f";
} else {
  $name2 = $ARGV[2];
}

open(IN, "<$file") || die;
while(<IN>) {
  if (/^\s\t*$/ || /^\s*\/\*/ || /^\s*\/\//) {
    next;
  }
  if (/$name1\s*\(.*{/) {
    $f1 = 1;
  }
  if (/$name2\s*\(.*{/) {
    $f2 = 1;
  }
  if ($f1) {
    $str1 .= $_;
    if (/^}/) {
      $f1 = 0;
    }
  }
  if ($f2) {
    $str2 .= $_;
    if (/^}/) {
      $f2 = 0;
    }
  }
}

my $diff = diff \$str1,  \$str2;
print $diff;