PHP sleep ( ) Function

The sleep () is another PHP inbuilt function that is utilized to postpone the execution of the ongoing content for a predefined number of seconds. The sleep () function acknowledges seconds as a boundary and returns TRUE on progress or FALSE on flop cases.

On the off chance that the call is intruded on by a sign, the sleep ( ) function returns a non-zero worth. On Windows, this worth will continuously be 192 while, on different stages, the return worth will be the number of seconds left to sleep.

Syntax

Parameters The sleep ( ) function in PHP acknowledges only one parameter.

Parameter	Description	Mandatory / Optional
$ seconds	This parameter is used to define the number of seconds the program will postpone. It must be in milliseconds.	Mandatory

The sleep () function returns TRUE on success or FALSE on a failure.

Exceptions

If the call is interfered with by a sign, the sleep ( ) function will return a non-zero assessment.
The worth of seconds passed as a parameter ought to be non-negative; else, this function will produce an E _ WARNING.

1. Example of sleep ( ) function

This example will help to understand sleep ( ) function completely

<!DOCTYPE html>
<html>
<body>

<?php
// displaying time
echo " <b> " .date('h:i:s') . " </b> " ." - as you can see the exact time before using the sleep function" ;
   
// delaying execution of the script for 2 seconds
sleep(2);
echo " <br> ";
echo " the sleep (2) will increase the display time by 2 seconds";
echo " <br> ";
   
// displaying time again
echo " <b> " .date('h:i:s') . " </b> " . " - as you can see the exact time after using the sleep function";

?> 

</body>
</html>

Output:

Example 2: Another example to help you about understanding sleep ( ) function.

<!DOCTYPE html>
<html>
<body>

<?php
// displaying time
echo " <b> " .date('h:i:s') . " </b> " ." - as you can see the exact time before using the sleep function" ;
   
// delaying execution of the script for 2 seconds
sleep(3);
echo " <br> ";
echo " the sleep ( 3 ) will increase the display time by 2 seconds";
echo " <br> ";
   
// displaying time again
echo " <b> " .date('h:i:s') . " </b> " . " - as you can see the exact time after using the sleep function";

?> 

</body>
</html>

Output:

Example 3: This function will allow the user to increase the time for a random interval using the sleep ( ) function

<!DOCTYPE html>
<html>
<body>

<?php
// displaying time
echo " <b> " .date('h:i:s') . " </b> " ." - as you can see the exact time before using the sleep function" ;
   
    
// using rand() function to randomly choose
// a value and delay execution of the script
echo " <br> ";
sleep(rand(1, 5));
echo " the rand ( 1 , 5 ) will increase the display time by any random seconds";
echo " <br> ";     
   
// displaying time again
echo " <b> " .date('h:i:s') . " </b> " . " - as you can see the exact time after using the sleep function";

?> 

</body>
</html> 

Output:

Example 4: the program to illustrate the use of multiple sleep function

<!DOCTYPE html>
<html>
<body>
<?php
// displaying time
echo " <b> " .date('h:i:s') . " </b> " ." - as you can see the exact time before using the sleep function" ;
  // delaying execution of the script for 10 seconds
sleep(10);
echo " <br> ";
echo " <b> " .date('h:i:s') . " </b> " . " - the sleep ( 10 ) will increase the display time by 10 seconds";
echo " <br> ";
// delaying execution of the script for 5 seconds again
sleep(5);
// displaying time again
echo " <b> " .date('h:i:s') . " </b> " ." - as you can see the exact time before using the sleep function as increased by ( 5 ) again " ;
?>
</body>
</html>

Output:

PHP time ( ) function

Example: Other method to perform sleep using loop

<!DOCTYPE html>
<html>
<body>

<?php
echo "time before using loop!" ."<br>";
echo date('h:i:s');
    $now = time();
    while ($now + 4 > time()) {
        // sit idle
    }

    echo "<br>" . "time after using loop"."<br>";
    echo date('h:i:s');
?>
</body>
</html>

Output:

This program shows the different ways of using the time constraint without using the sleep () function here. We have used the time () function instead. To perform the operation, we declared a variable and assigned it the time () function, which is another inbuilt PHP function, and later utilized the while loop and incremented the variable with + 4 so that it could proceed further to 4 seconds after the perfect execution of the program.

While it takes care of business, there are two issues with it. Right off the bat, time() has extremely low accuracy, just returning the number of entire seconds that have passed, which makes the entire thing very obscure. Also, PHP needs to stay there, circling a great many times while it pauses, basically sitting idle. A greatly improved arrangement is to utilize one of the two content rest capacities, sleep() and sleep(), which get some margin to stop execution as their main boundary.

Note: - The contrast between sleep() and usleep() is that sleep() requires various seconds as its boundary, while usleep() takes various microseconds - millionths of a second - as its boundary. Utilizing both of them is definitely more exact than the past time() circle, and the two of them enjoy their benefits - sleep() is better in the event that you needn't bother with the precision, and usleep() is better, assuming you do it straight.

PHP usleep ( ) function

Syntax

Example: This function will help to understand usleep ( ) function completely

<!DOCTYPE html>
<html>
<body>

<?php
// displaying time
echo " <b> " .date('h:i:s') . " </b> " ." - as you can see the exact time before using the sleep function" ;
   
// delaying execution of the script for 2 seconds
usleep(2000000);
echo " <br> ";
echo " the sleep (2) will increase the display time by 2 seconds";
echo " <br> ";
   
// displaying time again
echo " <b> " .date('h:i:s') . " </b> " . " - as you can see the exact time after using the sleep function";

?> 

</body>
</html>

Output:

Here in this program, as you can see, the sleep () function works exactly like the sleep() function but with only one difference, sleep takes a second as a parameter, whereas the usleep () function takes a millisecond as a parameter.