mt_srand（）和srand（） - 是否有必要将种子重置为随机数？

Question

I have a function in my code that uses a seed to get a predictable (based on the seed) set of random numbers.

$seed = 1234;
mt_srand($seed);

echo mt_rand(0,10);
echo mt_rand(0,10);
echo mt_rand(0,10);
echo mt_rand(0,10);

Is it necessary to call mt_srand() at the end of my function to reset it back to a random seed once I'm done with it?

Answer 1

Yes. The state of mt_rand() is global — if your function sets it to a fixed value, it will stay in that state after your function exits. While it's not ideal to call mt_srand(), as that would disrupt any other function that's trying to set a fixed seed, it's still preferable to leaving the random number generator in a non-random state.