A simple code to shift an array of integers to the left for a number of times

array_shift.c

#import <stdio.h>

void swap(int *a, int *b) {
    int tmp = *a;
    *a = *b;
    *b = tmp;
}

/* Precondition: n > 0 */
void reverse(int arr[], int n) {
    int i;
    for (i=0; i<n/2; ++i) {
        swap(arr+i, arr+n-i-1);
    }
}

/* Precondition: n > 0 */
void shift(int data[], int n, int i) {
    i = i % n;
    if (i < 0) {
        i += n;
    }
    if (i == 0) {
        return;
    }
    reverse(data, i);
    reverse(data+i, (n-i));
    reverse(data, n);
}
 
int main(int arg, char* argv[]) {
    int data[] = {1,2,3,4,5,6};
    shift(data, 6, -5);
    int i;
    for (i=0; i<6; ++i) {
        printf("%d ", data[i]);
    }
    return 0;
}

Example from Programming Pearls