Generate random number

Generating random numbers requires rand() function , This function requires a header file stdlib.h

If only rand() function , The generated random number is pseudo-random number , because rand（） Function before generating a random number , The seed of generating pseudo-random number sequence provided by the system is required ,rand Based on the value of this seed, a series of random numbers are generated . If the seed provided by the system does not change , Every time you call rand The sequence of pseudo-random numbers generated by function is the same . If you want to generate different random numbers every time , Need to change random seed , Time can be used to change the random seed of the system .

int rand_()// Generate random numbers 
{
	time_t ts;
	unsigned int n = time(&ts);// Acquisition time 
	srand(n);// Initialize random seed 
	int num = rand() % 100 + 1;// Random number range 1—100
	return num;
}