數組中數字的查找

（1）折半查找：

//折半查找
#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
int main()
{
 int arr[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
 int size = sizeof(arr) / sizeof(arr[0]);
 int to_find = 0;
 scanf("%d", &to_find);
 int left = 0;
 int right = size - 1;
 int mid = 0;
 while (left<=right)
 {
  mid = (left + right) / 2;
  if (arr[mid] < to_find)
  {
   left = mid + 1;
  }
  else if (arr[mid]>to_find)
  {
   right = mid - 1;
  }
  else
  {
   break;
  }
 }
 if (left <= right)
 {
  printf("找到了！下標爲：%d\n", mid);
 }
 else
 {
  printf("沒找到！\n");
 }
 system("pause");
 return 0;
}

（2）遍歷查找：

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
int main()
{
 int arr[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
 int to_find = 0;
 printf("請輸入要查找的數：");
 scanf("%d", &to_find);
 int size = sizeof(arr) / sizeof(arr[0]);
 int i = 0;
 for (; i < size;++i)
 {
  if (arr[i] == to_find)
  {
   break;
  }
 }
 if (i == size)
 {
  printf("沒找到！\n");
 }
 else
 {
  printf("找到了，下標爲：%d\n", i);
 }
 system("pause");
 return 0;
}