PHP random number code PHP generates random numbers method _php Tutorial

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Seed user-defined functions with microseconds as seeds
function seed ()
{
List ($msec, $sec) = explode (' ', Microtime ());
return (float) $sec;
}
Seeding the random number generator and invoking the return result of the seed function with the Srand function
Srand (Seed ());
The output generates random numbers, and the range of random numbers is 10-100.
echo rand (10,100);
?>
Isn't this the same as the one below? are random output 10-100 between the number of new students learning, may ask too simple OH
echo rand (10,100);
?>

Mt_rand (10,100);
Srand is a seed, if not set, the default is 1.
Rand is generally a fixed operation that uses seed to make parameters.

You'll find out if you try. Run Rand without seeding or setting a fixed seed
Then close the browser and open it again, and then run Rand.
You'll find the results are always the same.
But if a random number is used to seed, then the result of each run is approximate to the random

First say the rand () function, rand ([int min], [int max]) This function takes a random number between Min and Max. Without specifying the maximum and minimum range of random numbers, this function automatically takes a random number from 0 to Rand_max.

However, if only rand () is used, the random number is very chaotic and it is best to use the Srand () function to configure a new random number seed each time before taking a random number.

Explain the following usage (which is generally the case with these two functions):
Srand (Double) microtime () *1000000);
$rand _number= rand ();

Microtime () returns two values: the current millisecond and timestamp, we want to extract the random number, only a random number from the millisecond, (double) microtime () only returns the current millisecond value.
Microtime () is the number of milliseconds in seconds, and therefore the value is a decimal, multiplied by 1000000 to convert it to an integer.

; their workflow is as follows:
(1): First, give Srand () a "seed"; it is a value of type Unsigned_int.
(2): _ Then, call Rand (), which returns a random number (range between _0~32767) based on the value provided to Srand ()
(3): Call rand () as many times as needed, and get new random numbers continuously.
(4): Whenever you can provide a new "seed" for Srand (), further "Randomize" rand ()
Output results.

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