2.23 Halting Program Execution

You want to stop program execution for a couple of seconds or microseconds.

Technique

Use PHP's sleep() and usleep() functions, depending on how long you want your program to stop execution:

 <?php print "Hello World"; sleep(5); // Sleep 5 seconds print "This was done 5 seconds later"; usleep(70); // Sleep 70 microseconds print "This was done 5 seconds and 70 microseconds after the first Hello         World"; ?> 

Comments

The sleep() and the usleep() functions both make system calls to the sleep() function. However, the usleep() function converts the sleep time, like so:

 sleep((int) (useconds / 1000)); 

Sleeping is sometimes useful if you are working with sockets, or you are writing a daemon (CGI version of PHP only) that performs operations at regular intervals of time. (This usually can and should be done with cron.)