microtime function return current Unix timestamp with microseconds.
mixed microtime ([ bool $get_as_float = false ] )
This fucntion accept one optional parameter
get_as_float, if used and set to TRUE, microtime() will return a float instead of a string.
string microtime( )
This returns a string that contains both a Unix timestamp in seconds and a microsecond component. The returned string begins with the microsecond component, followed by the integer timestamp:
// prints the time now in the format "usec sec" // e.g., 0.34783800 1008553410 echo microtime( );
Generating random number seed
One common use of the function
microtime( ) is to generate the seed for a random-number generator:
// Generate a seed. $seed = (float)microtime( ) * 100000000; srand($seed);
Because the microsecond component appears at the start of the string returned from
microtime( ), the returned value can be converted to a float with the
(float) cast operator. Multiplying the float result by 100,000,000 ensures that you pass a suitably varying integer to the seeding function
srand( ). Random-number generation is covered in more detail in next tutorial.