Problem You want to extract part of a string, starting at a particular place in the string. For example, you want the first eight characters of a username entered into a form. Solution Use substr( ) to select your substring, as in Example 1-9. Example 1-9. Extracting a substring with substr( ) [sourcecode language="php"] <?php $substring = substr($string,$start,$length); $username = substr($_GET['username'],0,8); ?> [/sourcecode] Discussion If $start and $length are positive, substr( ) returns $length characters in the string, starting at $start. The first character in the string is at position 0. Example 1-10 has positive $start and $length. [sourcecode language="php"]print substr('watch out for that tree',6,5);[/sourcecode] Example 1-10 prints: out f If you leave out $length, substr( ) returns the string from $start to the end of the original string, as shown in Example 1-11. Example 1-11. Using substr( ) with positive start and no length [sourcecode language="php"]print substr('watch out for that tree',17);[/sourcecode] Example 1-11 prints: t tree If $start is bigger than the length of the string, substr( ) returns false.. If $start plus $length goes past the end of the string, substr( ) returns all of the string from $start forward, as shown in Example 1-12. Example 1-12. Using substr( ) with length past the end of the string [sourcecode language="php"]print substr('watch out for that tree',20,5);[/sourcecode] Example 1-12 prints: ree If $start is negative, substr( ) counts back from the end of the string to determine where your substring starts, as shown in Example 1-13. Example 1-13. Using substr( ) with negative start [sourcecode language="php"] print substr('watch out for that tree',-6); print substr('watch out for that tree',-17,5); [/sourcecode] Example 1-13 prints: t tree out f With a negative $start value that goes past the beginning of the string (for example, if $start is −27 with a 20-character string), substr( ) behaves as if $start is 0. If $length is negative, substr( ) counts back from the end of the string to determine where your substring ends, as shown in Example 1-14. Example 1-14. Using substr( ) with negative length [sourcecode language="php"] print substr('watch out for that tree',15,-2); print substr('watch out for that tree',-4,-1); [/sourcecode] Example 1-14 prints: hat tr tre See Also Documentation on substr( ) at http://www.php.net/substr.