A program to print all possible arrangements of `n` numbers. It accepts `n` as a command line parameter. Be careful, as there are `n!` possible permutations. With `n=10` or greater the program will be extremely slow.

rearrange.cpp

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

void rearrange(int *numbers, int index, int num) {
    int tmp;
    for (int i = index; i < num; ++i) {
        tmp = numbers[index];
        numbers[index] = numbers[i];
        numbers[i] = tmp;
        rearrange(numbers, index + 1, num);
        numbers[i] = numbers[index];
        numbers[index] = tmp;
    }
    if (index == num - 1) {
        for (int i = 0; i < num; ++i) {
            printf("%d ", numbers[i]);
        }
        printf("\n");
    }
}

int main(int argc, char **argv) {
    int num = atoi(argv[1]);

    int *numbers = new int[num];
    for (int i = 0; i < num; ++i) {
        numbers[i] = i + 1;
    }

    rearrange(numbers, 0, num);

    return 0;
}