Ask about how to generate random number which is not the same value at the same sec.

I want to generate random number which not have the same value at the same second. If you know how to do that, please tell me.This below is some part of program which generate the same random number at the same second.

code:

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srand((unsigned)time(NULL));

random_number = (rand() << 15 + rand());

random_number = random_number % MAX_RANDOM;

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