有15个数按升序存放在一个数组中，输入一个数，要求用折半查找法找出该数是数组中第几个元素的值，如果该数不在数组中，则输出“无此数”，请用C语言编程

以下是C语言代码：

#include <stdio.h>

int binarySearch(int arr[], int n, int x) {
int left = 0, right = n - 1;
while (left <= right) {
int mid = (left + right) / 2;
if (arr[mid] == x) {
return mid;
} else if (arr[mid] < x) {
left = mid + 1;
} else {
right = mid - 1;
}
}
return -1;
}

int main() {
int arr[15] = {1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29};
int n = sizeof(arr) / sizeof(arr[0]);
int x;
printf("请输入一个数：");
scanf("%d", &x);
int index = binarySearch(arr, n, x);
if (index == -1) {
printf("无此数\n");
} else {
printf("该数是数组中第%d个元素的值\n", index + 1);
}
return 0;
}