PHP随机值uniqid

[php]
<?php
header("content-type:text/html;charset=utf-8");
echo "默认随机值:".uniqid();
echo "<br>默认随机值加前缀:".uniqid("s_");
echo "<br>默认随机值加前后缀:".uniqid("s_",true);
?>
[/php]