PHP array_rand weird behaviour - php

Question

I was trying to create a simple password generator and noted that array_rand() returns the same results. Here is the code:
<?php
function generatePass() {
$password = '';
$a = explode(' ', 'q w e r t y u i o p a s d f g h j k l z x c v b n m');
for($i=0; $i < rand(1,200); $i++) {
$password .= $a[array_rand($a)];
}
return $password;
}
$r = 0;
while ($r <= 10000) { #generating 10 000 passwords
$total[] = generatePass();
$r++;
}
echo '<pre>';
print_r($total);
echo '</pre>';
?>
The $total array basically contains the same results repeated over and over again; if I refresh the page, only the order of elements changes, and not their values.
The question is: is this an expected behaviour or am I doing something wrong?
Thak you for your attention.

Answer 1

Reseed the random number generator with srand() just prior to calling array_rand.
srand();
$password .= $a[array_rand($a)];

Answer 2

I think it should be your PHP version. I just copied your code into my localhost server and it worked fine. I'm using PHP 5.5.9-1ubuntu4.7, you should try it or a newer version.
By the way, if you can't update your PHP version, use this modified version of your code:
<?php
function generatePass() {
$password = '';
// Put all letters into an array.
$letters = array('q','w','e','r','t','y','u','i','o','p','a','s','d','f','g','h','j','k','l','z','x','c','v','b','n','m');
for($i=0; $i < rand(1,200); $i++) {
// Select a random letter with rand() command inside the brackets of the array.
$password .= $letters[rand(0,25)];
}
return $password;
}
$r = 0;
while ($r <= 10000) { #generating 10 000 passwords
$total[] = generatePass();
$r++;
}
echo '<pre>';
print_r($total);
echo '</pre>';
?>

Answer 3

Seeding the random generator isn't needed since version 4.2.0
Try using mt_rand() for a better generation.
http://php.net/manual/en/function.mt-rand.php
Edit:
I think you actually want
$a = explode(' ', 'q w e r t y u i o p a s d f g h j k l z x c v b n m');
$end = mt_rand(1,200);
$password = '';
for($i=0; $i < $end; $i++) {
$password .= $a[array_rand($a)];
}

Answer 4

I took the time for you and wrote the generator.
I got it to generate 10000 unique passwords and code is efficient:
<?php
function generatePass() {
$password = '';
$lib = 'q w e r t y u i o p a s d f g h j k l z x c v b n m';
$a = explode(' ', $lib);
//remove random char
for($i=0; $i < mt_rand(1,49); $i++) {
shuffle($a);
//get Random Char
$password .= $a[mt_rand(0,count($a)-1)];
}
return $password;
}
$len = 10000; // total number of numbers
$range = array();
foreach(range(0, $len - 1) as $i){
while(in_array($num = generatePass(), $range)){}
$range[] = $num;
}
echo '<pre>';
print_r($range);
echo '</pre>';