I have written a simple function to generate a random string in PHP. It was made to generate a string with uppercase, lowercase and numeric values. It can be modified to accept any ASCII characters and can generate a string of any length.

This function may also help understanding passing variables by reference and recursion.

Function

function generateRandomString( $length, &$string )
{
	// RANDOM TO CHOOSE 1. UPPERCASE / 2. LOWERCASE / 3. NUMBER
	$which = mt_rand( 1, 3 );
	switch( $which )
	{
		case 1:
			$min = 65; $max = 90;
			break;
		case 2:
			$min = 97; $max = 122;
			break;
		case 3:
			$min = 48; $max = 57;
			break;
	}

	// GET RANDOM NUMBER FOR CHARACTER
	$rand = mt_rand( $min, $max );

	// CONVERT ASCII TO CHAR AND APPEND TO STRING
	$string .= chr( $rand );

	// IF EQUAL TO OR GREATER THAN LENGTH THEN RETURN
	if( strlen($string) >= $length ) return;

	// RECURSION - BUILD THE STRING
	generateRandomString( $length, $string );
}

Usage

generateRandomString( 8 , $string );

Posted by Beau Durrant