Srand (double) microtime () * 1000000)

There are four steps: 1. Execute microtime () to get the current number of microseconds. 2. Convert the obtained Number of microseconds to the double type. 3. Multiply the converted number by 10000004: seeding a random number generator. The result of step 3 is that Rand generates a pseudo random integer between 0 and rand_max. The value of rand_max varies with srand () based on different platforms () function is used to broadcast the seed of the random number generator.

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