how to sort arrays in c language

/*
Example: how to sort an int array in C language
*/

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

void swap(int* xp, int* yp)
{
    int temp = *xp;
    *xp = *yp;
    *yp = temp;
}

// selection sort function
void selectionSort(int arr[], int n)
{
    int i, j, min_idx;

    //  iterate through array
    for (i = 0; i < n - 1; i++) {

        // Find the smallest element in an unsorted array
        min_idx = i;
        for (j = i + 1; j < n; j++)
            if (arr[j] < arr[min_idx])
                min_idx = j;

        // Find the minimum value and exchange it with the first element
        swap(&arr[min_idx], &arr[i]);
    }
}

int main(int argc, char const *argv[])
{
    int arr[] = {70,35,40,1,8,12,3,6,5};
    int n = sizeof(arr)/sizeof(int);

    printf("before sort\n");
    for(int i=0 ; i< n ; i++)
    {
        printf("%d, ", arr[i]) ;
    }
    selectionSort(arr,n);
    printf("\nafter sort\n");
    for(int i=0 ; i< n ; i++)
    {
        printf("%d, ", arr[i]) ;
    }
    return 0;
}