Joel Coding Problem binary_search

#include <stdio.h>
#include <assert.h>

#define uint unsigned int

int binary_search(const int arr[], int len, int val) {
  if (arr == NULL) {
    return -1;
  }
  if (len < 1) {
    return -1;
  }

  int left = 0;
  int right = len - 1;
  int ans = -1;
  while (left <= right) {
    int mid = (left + right) / 2;
    if (arr[mid] == val) {
      ans = mid;
      break;
    } else if (arr[mid] > val) {
      right = mid - 1;
    } else {
      left = mid + 1;
    }
  }

  return ans;
}

#define TEST_NUM 22
int main() {
  int i;
  int arr[TEST_NUM] = {0, };
  for(i=0; i < TEST_NUM; ++i){
    arr[i] = i;
  }

  for (int i = 0; i < TEST_NUM; ++i) {
    assert(binary_search(arr, sizeof(arr)/sizeof(int), i) == i);
  }

  assert(binary_search(arr, sizeof(arr)/sizeof(int), i) == -1);

  return 0;
}