How to generate random numbers in c language

The rand() function can be used in C language to generate random numbers, which can generate random integers between 0 and RAND_MAX (32767). The random numbers are controlled by random seeds. You can use srand() to set the random number seeds. The default random number seed is 1; if you want to generate a random integer within 1-100, you need to use "rand() 0".

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In C language, random numbers can be generated by using the rand function. The rand function generates integers in a specified order. However, the randomness generated in C language is not truly random and can sometimes be called pseudo-random numbers.

Before using rand() to generate random numbers, you need to use the initialization function srand (unsigned seed) of the random generator to initialize the pseudo-random number sequence. Seed is also called random seed, which means that if the seed provided is the same every time , then the random values ​​generated in each round are also the same, so they are called pseudo-random numbers, so a different seed value needs to be provided each time to achieve complete randomness. Usually in C language we use the time function time ( null) as seed, because the time value is different every second

Example:

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int main()
{
    srand(1);
    int i;
    for (i = 0; i < 10; i++)
    printf("%d, ", rand()%11); 
}

The result is: 8, 9, 9, 1, 7, 5, 5, 10, 1, 0,

The above result is the same no matter how many times it is run. The reason is that the random seed seed is 1

but when we change the seed value to time( null) The situation is different

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int main()
{
    srand(time(NULL));
    int i;
    for (i = 0; i < 10; i++)
    printf("%d, ", rand()%11); 
}

The results are as follows: 6, 3, 4, 5, 5, 9, 8, 10, 10, 4

Click again: 6 , 4, 2, 4, 3, 2, 5, 1, 2, 9

Here, due to the effect of time(null), the seed keeps changing, that is, new random numbers are constantly generated

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