要用c++的cincout

好的，以下是使用C++的代码实现：

#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <iomanip>

using namespace std;

int main()
{
    ifstream fin("scores.txt"); // 打开scores.txt文件
    vector<int> scores;
    int score;
    while (fin >> score) {
        scores.push_back(score); // 读入数据
    }
    fin.close(); // 关闭文件

    int score_90_100 = 0, score_80_89 = 0, score_70_79 = 0, score_60_69 = 0, score_below_60 = 0;
    for (int i = 0; i < scores.size(); i++) { // 统计各分数段的人数
        if (scores[i] >= 90) {
            score_90_100++;
        } else if (scores[i] >= 80) {
            score_80_89++;
        } else if (scores[i] >= 70) {
            score_70_79++;
        } else if (scores[i] >= 60) {
            score_60_69++;
        } else {
            score_below_60++;
        }
    }

    int total_students = scores.size(); // 统计总人数
    double average_score = accumulate(scores.begin(), scores.end(), 0.0) / total_students; // 计算平均成绩
    int max_score = *max_element(scores.begin(), scores.end()); // 计算最高分
    int min_score = *min_element(scores.begin(), scores.end()); // 计算最低分

    // 计算各分数段的占比（保留小数点后四位）
    double percent_90_100 = round(score_90_100 * 10000.0 / total_students) / 100.0;
    double percent_80_89 = round(score_80_89 * 10000.0 / total_students) / 100.0;
    double percent_70_79 = round(score_70_79 * 10000.0 / total_students) / 100.0;
    double percent_60_69 = round(score_60_69 * 10000.0 / total_students) / 100.0;
    double percent_below_60 = round(score_below_60 * 10000.0 / total_students) / 100.0;

    ofstream fout("result.txt"); // 打开result.txt文件
    fout << "总人数：" << total_students << endl;
    fout << fixed << setprecision(2); // 设置小数点后两位
    fout << "平均成绩：" << average_score << endl;
    fout << "最高分：" << max_score << endl;
    fout << "最低分：" << min_score << endl;
    fout << "90~100分人数：" << score_90_100 << "，占比：" << percent_90_100 << "%" << endl;
    fout << "80~89分人数：" << score_80_89 << "，占比：" << percent_80_89 << "%" << endl;
    fout << "70~79分人数：" << score_70_79 << "，占比：" << percent_70_79 << "%" << endl;
    fout << "60~69分人数：" << score_60_69 << "，占比：" << percent_60_69 << "%" << endl;
    fout << "小于60分人数：" << score_below_60 << "，占比：" << percent_below_60 << "%" << endl;
    fout.close(); // 关闭文件

    return 0;
}

运行完上述代码后，会在当前目录下生成一个result.txt文件，其中包含了统计结果。