编程实现：利用折半查找算法实现在数据序列{2,3,6,33,45,66,88,100}分别查找关键字6和89的结果，找到输出位序，找不到输出相应提示信息。C语言实现

### 回答1：
以下是C语言实现折半查找算法的代码：

#include <stdio.h>

int binarySearch(int arr[], int left, int right, int key) {
    while (left <= right) {
        int mid = left + (right - left) / 2;
        if (arr[mid] == key) {
            return mid;
        } else if (arr[mid] < key) {
            left = mid + 1;
        } else {
            right = mid - 1;
        }
    }
    return -1;
}

int main() {
    int arr[] = {2, 3, 6, 33, 45, 66, 88, 100};
    int n = sizeof(arr) / sizeof(arr[0]);
    int key1 = 6, key2 = 89;
    int index1 = binarySearch(arr, 0, n - 1, key1);
    int index2 = binarySearch(arr, 0, n - 1, key2);

    if (index1 != -1) {
        printf("The index of %d is %d\n", key1, index1);
    } else {
        printf("%d not found in the array\n", key1);
    }

    if (index2 != -1) {
        printf("The index of %d is %d\n", key2, index2);
    } else {
        printf("%d not found in the array\n", key2);
    }

    return 0;
}

输出结果为：

The index of 6 is 2
89 not found in the array

可以看到，程序成功找到了关键字6的位序，但未找到关键字89，并输出了相应提示信息。

### 回答2：
下面是一种用C语言实现的折半查找算法来查找关键字6和89在数据序列{2,3,6,33,45,66,88,100}中的结果：

#include<stdio.h>

int binarySearch(int arr[], int low, int high, int key) {
    while (low <= high) {
        int mid = low + (high - low) / 2;

        if (arr[mid] == key) {
            return mid;
        }

        if (arr[mid] < key) {
            low = mid + 1;
        }
        else {
            high = mid - 1;
        }
    }

    return -1;
}

int main() {
    int arr[] = {2, 3, 6, 33, 45, 66, 88, 100};

    int key1 = 6;
    int key2 = 89;

    int index1 = binarySearch(arr, 0, sizeof(arr) / sizeof(arr[0]) - 1, key1);
    int index2 = binarySearch(arr, 0, sizeof(arr) / sizeof(arr[0]) - 1, key2);

    if (index1 != -1) {
        printf("关键字6的位置是%d\n", index1);
    }
    else {
        printf("找不到关键字6\n");
    }

    if (index2 != -1) {
        printf("关键字89的位置是%d\n", index2);
    }
    else {
        printf("找不到关键字89\n");
    }

    return 0;
}

运行该程序，输出结果为：

关键字6的位置是2
找不到关键字89

根据输出结果可知，关键字6位于数据序列的第3个位置，而关键字89在数据序列中找不到。

### 回答3：
#include <stdio.h>

int binarySearch(int arr[], int size, int target) {
int left = 0, right = size - 1;

while (left <= right) {
int mid = left + (right - left) / 2;

if (arr[mid] == target) {
return mid + 1;
} else if (arr[mid] < target) {
left = mid + 1;
} else {
right = mid - 1;
}
}

return -1;
}

int main() {
int arr[] = {2, 3, 6, 33, 45, 66, 88, 100};
int size = sizeof(arr) / sizeof(arr[0]);

int target1 = 6;
int result1 = binarySearch(arr, size, target1);
if (result1 != -1) {
printf("关键字6的位序为：%d\n", result1);
} else {
printf("未找到关键字6\n");
}

int target2 = 89;
int result2 = binarySearch(arr, size, target2);
if (result2 != -1) {
printf("关键字89的位序为：%d\n", result2);
} else {
printf("未找到关键字89\n");
}

return 0;
}

编程实现了折半查找算法在给定数据序列{2,3,6,33,45,66,88,100}中查找关键字6和89的结果。查找关键字6时，通过折半查找算法找到了该关键字在序列中的位置，即第3位；而查找关键字89时，在序列中没有找到该关键字，输出相应提示信息"未找到关键字89"。