Random string in PHP using criteria

Question

I need to generate random string using below criteria in PHP. How can I implement the same in PHP?

1. String length must be 12
2. 4 char must be from [a-z]
3. 4 char must be from [A-Z]
4. 4 char must be from [0-9]

Is it possible in PHP?

Answer 1

One way of achieving it :

$lowerCaseLetters = range( 'a' ,'z' );
$upperCaseLetters = range( 'A' ,'Z' );
$numericDigits = range( '0' ,'9' );

$randomString = '';

for( $i = 0; $i < 4; $i++ )
{
    $randomNumber = rand( 0 ,( count( $lowerCaseLetters ) - 1 ) );
    $randomString .= $lowerCaseLetters[ $randomNumber ];

    $randomNumber = rand( 0 ,( count( $upperCaseLetters ) - 1 ) );
    $randomString .= $upperCaseLetters[ $randomNumber ];

    $randomNumber = rand( 0 ,( count( $numericDigits ) - 1 ) );
    $randomString .= $numericDigits[ $randomNumber ];
}

$randomString = str_shuffle( $randomString );

echo $randomString;

Results :

OkB7Js2c8V8j
7znl4LCv1UR6
F2nYM8cx3yF9