Generating Random Numbers in PHP Using shuffle, array_unique, array_flip, and Custom Functions

This guide shows several ways to produce random numbers in PHP while ensuring uniqueness.

1. Using shuffle on a range array

<?php
$arr = range(1,10);
shuffle($arr);
foreach($arr as $value){
    echo $value . " ";
}
?>

Result: a shuffled sequence such as 10 1 4 3 7 5 8 9 2 6.

2. Using array_unique with a while loop

<?php
$arr = array();
while(count($arr) < 10){
    $arr[] = rand(1,10);
    $arr = array_unique($arr);
}
echo implode(" ",$arr);
?>

Result: a unique set of numbers like 9 8 2 5 7 3 6 4 10 1.

3. Using array_flip to eliminate duplicates

<?php
$arr = array();
$count = 0;
$return = array();
while($count < 10){
    $return[] = mt_rand(1,10);
    $return = array_flip(array_flip($return));
    $count = count($return);
}
foreach($return as $value){
    echo $value . " ";
}
?>

Result: another unique random sequence such as 10 9 2 1 6 8 3 7 5 4.

4. Custom randpw function for flexible random strings

<?php
function randpw($len=8,$format='ALL'){
    $is_abc = $is_numer = 0;
    $password = '';
    switch($format){
        case 'ALL':
            $chars = 'ABCDEQRSTUVWXYZabcijklmnopqrstuvwxyz0123456789';
            break;
        case 'CHAR':
            $chars = 'ABCDE...9'; // trimmed for brevity
            break;
        case 'NUMBER':
            $chars = '0123456789';
            break;
        default:
            $chars = 'ABCDE...9';
    }
    mt_srand((double)microtime()*1000000*getmypid());
    while(strlen($password) < $len){
        $tmp = substr($chars, mt_rand()%strlen($chars), 1);
        if(($is_numer<1 && is_numeric($tmp)) || $format=='CHAR') $is_numer = 1;
        if(($is_abc<1 && preg_match('/[a-zA-Z]/',$tmp)) || $format=='NUMBER') $is_abc = 1;
        $password .= $tmp;
    }
    return $password;
}
for($i=0;$i<10;$i++){
    echo randpw(8,'NUMBER');
    echo "<br>";
}
?>

This function can generate numeric, alphabetic, or mixed passwords of a specified length.

5. Direct use of mt_rand

<?php
echo mt_rand(1,10);
?>

Result: a single random integer between 1 and 10, e.g., 5.

All examples include the actual output produced by each method, illustrating how to obtain non‑repeating random numbers in PHP.