PHP Find / Extract Substrings

Posted on in Categories , , , , , , last updated March 17, 2010

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:

if (strpos($input, '#') === true ) {
	print '# symbol found in input';
	print 'There was no # symbol found in input';	

Extracting a substring with substr()

$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.

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.