Question

How to iterate an array from the middle outward (stepping left and right alternately) in C

Answer 1

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

int main(void) {
    int arr[] = {0,1,2,3,4,5,6,7};
    size_t n = sizeof(arr) / sizeof(arr[0]);

    // Middle index for even-sized arrays
    size_t mid = n / 2;

    // Left starts just before mid, right starts at mid
    ssize_t left = mid - 1;
    ssize_t right = mid;

    // Iterate outward from the middle
    while (left >= 0 || right < (ssize_t)n) {

        if (right < (ssize_t)n) {
            printf("%d ", arr[right]);
            right++;
        }

        if (left >= 0) {
            printf("%d ", arr[left]);
            left--;
        }
    }

    return 0;
}



/*
run:

4 3 5 2 6 1 7 0

*/

 

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