Generation of random numbers in C language [detailed explanation]

Catalog

• • • One 、rand function and srand function
    • Two 、 Generate range random number formula
    • 3、 ... and 、 Random number instance ： Select sort, etc

One 、rand function and srand function

stay C The random function commonly used in language is rand function , It can be generated randomly 0 ~ rand_max The random number , The maximum value varies with the type of definition ,rand The function is contained in the header file stdlib.h in .

#include <stdio.h>
#include <stdlib.h>
int main()
{
    int a=rand();
    printf("%d",a);
    return 0;
}

Running results …………………………………………

You will find that the random number generated each time is the same , because rand The random number generated by a function is a pseudo-random number , It is calculated according to a number and a formula , This number we call “ seeds ”, But this seed is a fixed value after the system is started .

If you want to generate different random numbers every time , that , We're going to use srand function .

srand() The function prototype is ：

void srand (usigned int seed);

rand() When generating random numbers , If you use