Q. How do I find out if a string stored in a variable contains a particular substring using PHP? How do I find out (extract) first 5 character of a particular string using Apache and PHP?

A. You need to use the following php functions:

a] strpos() : Find position of first occurrence of a string

b] substr() : Return part of a string

c] substr_replace() : Replacing a substring

Find position of first occurrence of a string with strpos()

Find out if $input contains a # symbol or not:

<?php
if (strpos($input, '#') === true ) {
	print '# symbol found in input';
}
else{
	print 'There was no # symbol found in input';	
}
?>

Extracting a substring with substr()

<?php
$input = "nixCraft blog";
// substr syntax
// $substring = substr($string,$start,$length);
// Get first 5 chars of $input
$data = substr($input,0,5);
print $data; 
?>

This is useful for finding out usernames and other data.