Question

How to random (shuffle) array of integers in C

Answer 1

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

void swap(int arr[], int i, int j) {
    int temp = arr[i];
    arr[i] = arr[j];
    arr[j] = temp;
}

void shuffle(int arr[], int n) {
    for (int i = n - 1; i >= 1; i--) {
        int j = rand() % (i + 1);
        swap(arr, i, j);
    }
}


int main(int argc, char **argv)
{
    int arr[] = { 1, 2, 3, 4, 5, 6, 7, 9, 9, 0};
    int len = sizeof(arr) / sizeof(arr[0]);

    srand(time(NULL));

    shuffle(arr, len);

    for (int i = 0; i < len; i++) {
        printf("%3d", arr[i]);
    }

    return 0;
}



/*
run:

  3  7  9  5  2  4  9  1  0  6

*/

 

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