InsertSort.c

#define size(array)     (sizeof(array) / sizeof(array[0]))

void insertsort(int *a, int len)
{
  int j;
  for (j=1; j<len; j++) {
    int key = a[j];
    int i = j-1;
    while (i>=0 && a[i]>key) {
      a[i+1] = a[i];
      i = i-1;
    }
    a[i+1] = key;
  }
}

int main()
{
  int a[] = {10, 2, 4, 6, 7};
  insertsort(a,size(a));

  int i;
  for (i = 0; i < size(a); ++i) {
     printf("%d\n",a[i]);     
   }

  return 0;
}