php字符串替换函数substr_replace()用法实例

<?php
$string = "Warning: System will shutdown in NN minutes!";
$pos = strpos($string, "NN");
print(substr_replace($string, "15", $pos, 2)."\n");
sleep(10*60);
print(substr_replace($string, "5", $pos, 2)."\n");
?>

Warning: System will shutdown in 15 minutes!
(10 minutes later)
Warning: System will shutdown in 5 minutes!