C语言基础：二分查找法示范代码

C语言基础：二分查找法演示代码

#include <stdio.h>
int binary_search(int array[], int value, int size)
 {
   int found = 0;
   int high = size, low = 0, mid;
   mid = (high + low) / 2;
   printf("\n\nLooking for %d\n", value);
   while ((! found) && (high >= low))
    {
      printf("Low %d Mid %d High %d\n", low, mid, high);
      if (value == array[mid])
        found = 1;
      else if (value < array[mid])
        high = mid - 1;
      else
        low = mid + 1;
      mid = (high + low) / 2;
   }
  return((found) ? mid: -1);
 }
int main(void)
 {
   int array[100], i;
   for (i = 0; i < 100; i++)
     array[i] = i;
   printf("Result of search %d\n", binary_search(array, 33, 100));
   printf("Result of search %d\n", binary_search(array, 75, 100));
   printf("Result of search %d\n", binary_search(array, 1, 100));
   printf("Result of search %d\n", binary_search(array, 1001, 100));
return 1;
 }
  

输出结果

Looking for 33
Low 0 Mid 50 High 100
Low 0 Mid 24 High 49
Low 25 Mid 37 High 49
Low 25 Mid 30 High 36
Low 31 Mid 33 High 36
Result of search 33
Looking for 75
Low 0 Mid 50 High 100
Low 51 Mid 75 High 100
Result of search 75
Looking for 1
Low 0 Mid 50 High 100
Low 0 Mid 24 High 49
Low 0 Mid 11 High 23
Low 0 Mid 5 High 10
Low 0 Mid 2 High 4
Low 0 Mid 0 High 1
Low 1 Mid 1 High 1
Result of search 1
Looking for 1001
Low 0 Mid 50 High 100
Low 51 Mid 75 High 100
Low 76 Mid 88 High 100
Low 89 Mid 94 High 100
Low 95 Mid 97 High 100
Low 98 Mid 99 High 100
Low 100 Mid 100 High 100
Result of search -1