用C语言写程序:+有15个数按由大到小顺序存放在一个数组中,输入一个数,要求用

根据提供的引用内容，以下是用C语言编写的折半查找法程序：

#include <stdio.h>

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

int main() {
    int arr[] = {15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1};
    int n = sizeof(arr) / sizeof(arr[0]);
    int x;
    printf("请输入要查找的数：");
    scanf("%d", &x);
    int result = binarySearch(arr, 0, n - 1, x);
    if (result == -1)
        printf("无此数\n");
    else
        printf("该数是数组中第%d个元素的值\n", result + 1);
    return 0;
}