What is my mistak with rand function ?

imami

I use this code to generate a 12 digits random number

<?php
for($i=0;$i<30;$i++)
	echo rand(100000000000,999999999999) . '<br />';
?>

What is expect is to show me 30 line of 12 digits numbers
but the result is somethin like this :

I have three problems now .
1 - I have some negative numbers , why ?
2 - This numers doesn't have 12 digits . why ?
3 - I don't have the above problems with random number with 11 digits

<?php
for($i=0;$i<30;$i++)
	echo rand(10000000000,99999999999) . '<br />';
?>

Why ?

coldwerturkey

read me to find out why