What is the difference between php mt_rand() and rand()

Difference: 1. If the parameter is omitted, the random number generated by rand() is between 0 and getrandmax(), while the random number generated by mt_rand() is between 0 and mt_getrandmax(); 2. The performance of mt_rand() is better than rand().

The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

rand() and mt_rand() have both functions There are two forms of use to generate a random integer:

int rand() 
int mt_rand()

int rand(int $min, int $max)
int mt_rand($min, $max)

For the first form:

The random number generated by rand() is from 0 to Between getrandmax()

The random number generated by mt_rand() is between 0 and mt_getrandmax()

For the second form:

rand() generates a random number from $min to $max

mt_rand() generates a random number from $min to $max

Comparison:

mt_rand() is a better random number generator because it sows a better random number seed than rand(); and its performance is 4 times faster than rand(), mt_getrandmax( ) represents a larger numerical range

PS: Generation of random floating point numbers

There is a demo in the PHP manual

function randomFloat($min = 0, $max = 1) {
    return $min + mt_rand() / mt_getrandmax() * ($max - $min);
}

var_dump(randomFloat());
var_dump(randomFloat(2, 20));

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