写一个用二分按照学生成绩排名的程序c++

Sure, here is an example implementation of a C program that sorts students' scores using binary search:

#include <stdio.h>
#include <stdlib.h>

int cmp(const void *a, const void *b) {
    return *(int*)a - *(int*)b;
}

int binary_search(int *arr, int n, int x) {
    int l = 0, r = n - 1;
    while (l <= r) {
        int mid = l + (r - l) / 2;
        if (arr[mid] == x) return mid;
        if (arr[mid] < x) l = mid + 1;
        else r = mid - 1;
    }
    return -1;
}

int main() {
    int n;
    scanf("%d", &n);
    int scores[n];
    for (int i = 0; i < n; i++) {
        scanf("%d", &scores[i]);
    }
    qsort(scores, n, sizeof(int), cmp);
    printf("Sorted scores:\n");
    for (int i = n - 1; i >= 0; i--) {
        printf("%d\n", scores[i]);
    }
    int x;
    printf("Enter a score to search for:\n");
    scanf("%d", &x);
    int idx = binary_search(scores, n, x);
    if (idx == -1) {
        printf("Score not found!\n");
    } else {
        printf("Score found at index %d.\n", idx);
    }
    return 0;
}

This program takes in N scores as input, sorts them using quicksort, and then prints them out in descending order. It also prompts the user to search for a specific score using binary search and returns the index at which it was found.