I want to generate thirty unique alphanumeric strings in PHP loop - php

Question

<?php
// Set length of the string
$length = 30;
$random = substr(md5(rand()), 0, 15);
// Use for-loop to generate thirty unique alphanumeric strings
For($i=0; $i<$length;) {echo $random.$i++."<br />";
The code above generates something like 5523d651bfb642b0, 5523d651bfb642b1, 5523d651bfb642b2, 5523d651bfb642b3 etc. The next value is just too easily predictable. I want something totally different like when I refresh the page in the browser. If I remove loop and just echo $random, the page generates a totally different string every time I refresh the page. How do I generate something totally different like 5523d651bfb642b0, 2yyd00nngbh201km, 78gdfmpqg01597v etc using loop? Thanks.

Answer 1

function generateRandomString($length = 30) {
$characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
$charactersLength = strlen($characters);
$randomString = '';
for ($i = 0; $i < $length; $i++) {
$randomString .= $characters[rand(0, $charactersLength - 1)];
}
return $randomString;
}
$i = 0;
$times_to_run = 30;
while ($i++ < $times_to_run)
{
generateRandomString();
}

Answer 2

If you're using PHP 7, it's easy to generate a random string:
$bytes = random_bytes(5); //random. Increase input for more bytes
$code = bin2hex($bytes); // eg: 385e33f741
Before PHP 7, I would generate an alphanumeric code with a function
function getRandomString($length){
$chars = 'abcdefghijklmnopqrstuvwxyz0123456789';
$result = '';
while(strlen($result)<$length) {
$result .= $chars{mt_rand(0,strlen($chars)-1)};
}
return $result;
}
To get a 10-character random code, you just call:
$randomString = getRandomString(10);
You can add more characters to $chars ofcourse