在PHP中获取微观或毫秒的时差

Question

I am trying to find time required to execute some function using php. I want accuracy of milli or micro seconds but i get difference in seconds.

The code is as follows:

<?php

$time_start = microtime(true);


usleep(2000000);

$time_end = microtime(true);

$time = $time_end - $time_start;

echo "Did nothing in $time micro seconds
";


?>

The output i get is 2 micro seconds but it should be 2000000 micro seconds according to program.

If i keep usleep(100) it will give me 0 difference.

Please help me with some solution to this.

Answer 1

The result of microsecond(true) is a float, "which represents the current time in seconds" and "accurate to the nearest microsecond" (http://php.net/microtime). Meaning decimals before the comma are in seconds and the decimals after the comma represent the microseconds.

Therefore the example in the manual is more correct than your variant:

echo "Did nothing in $time seconds
";

If the execution takes exactly two seconds, it will output:

Did nothing in 2 seconds

If the execution takes two seconds and 500 milliseconds, it will output:

Did nothing in 2.5 seconds