#!/usr/bin/perl -w
use strict;

$_= "This/is/a/test";
s<(\w+)/><$`$1\n>g;
print $_,$/,$/;

$_= "This/is/a/test";
s<(\w+)/><substr( $_, 0, pos $_). "$1\n">ge;
print $_,$/;

##</code><code>##

This
This/is
This/is/a
test

Use of uninitialized value in substr at - line 9.
Use of uninitialized value in substr at - line 9.
Use of uninitialized value in substr at - line 9.
This
is
a
test