C++作业-成绩统计

成绩统计

1）编写一个函数randScore，生成一个[0,100]区间的整数。（提示：使用rand函数）

int randScore(){
    int num = rand() % 101;
    return num;
}

2）编写一个函数使用上面的randScore函数，随机生成全班同学某门功课的成绩。

void stuRandomScore(int stuScore[]){
    for (int i = 0; i < stuNum; i++)
        stuScore[i] = randScore();
    for (int i = 0; i < stuNum; i++)
        cout << "第" << i + 1 << "位同学成绩为：" << stuScore[i] << endl;
}

3）编写一个函数Score2Grade，实现百分制到五分制转换。

void Score2Grade(int stuScore[]){
    for (int i = 0; i < stuNum; i++)
        if (stuScore[i] >= 50)
            score2Grade[i] = float(stuScore[i]) / 10 - 5;
        else
            score2Grade[i] = 0;
    for (int i = 0; i < stuNum; i++)
        cout << "第" << i + 1 << "位同学绩点：" << score2Grade[i] << endl;
}

4）编写一个函数，使用Score2Grade，统计全班同学不同分数等级（Grade）的比例。

void PersentGrade(float score2Grade[5]){
    int per[5] = {0};
    for (int i = 0; i < stuNum; i++){
        if (score2Grade[i] >= 0 && score2Grade[i] <= 1)
            per[0]++;
        if (score2Grade[i] > 1 && score2Grade[i] <= 2)
            per[1]++;
        if (score2Grade[i] > 2 && score2Grade[i] <= 3)
            per[2]++;
        if (score2Grade[i] > 3 && score2Grade[i] <= 4)
            per[3]++;
        if (score2Grade[i] > 4 && score2Grade[i] <= 5)
            per[4]++;
    }
    for (int i = 0; i < 5; i++){
        persentGrade[i] = float(per[i]) / stuNum;
        cout << "比例为：" << persentGrade[i] << endl;
    }
}

5）编写一个函数，计算全班同学的平均成绩与标准差。

float Average(int *stuScore){
    int sum = 0;
    for (int i = 0; i < stuNum; i++) // 求和
        sum += stuScore[i];
    return float(sum) / stuNum; // 得到平均值
}
float StandardDeviation(int *stuScore){
    float sum = 0;
    float average = Average(stuScore);
    for (int i = 0; i < stuNum; i++) // 求和
        sum += pow(stuScore[i] - average, 2);
    return sqrt(sum / stuNum);
}

程序汇总如下

#include <iostream>
#include <stdlib.h> 
#include <math.h>
using namespace std;
class MyScores{
public:
    int stuNum;
    int *stuScore;
    float *score2Grade;
    float *persentGrade;
    int randScore(){
        int num = rand() % 101;
        return num;
    }
    void stuRandomScore(int stuScore[]){
        for (int i = 0; i < stuNum; i++)
            stuScore[i] = randScore();
        for (int i = 0; i < stuNum; i++)
            cout << "第" << i + 1 << "位同学成绩为：" << stuScore[i] << endl;

    }
    void Score2Grade(int stuScore[]){
        for (int i = 0; i < stuNum; i++)
            if (stuScore[i] >= 50)
                score2Grade[i] = float(stuScore[i]) / 10 - 5;
            else
                score2Grade[i] = 0;
        for (int i = 0; i < stuNum; i++)
            cout << "第" << i + 1 << "位同学绩点：" << score2Grade[i] << endl;
    }
    void PersentGrade(float score2Grade[5]){
        int per[5] = {0};
        for (int i = 0; i < stuNum; i++){
            if (score2Grade[i] >= 0 && score2Grade[i] <= 1)
                per[0]++;
            if (score2Grade[i] > 1 && score2Grade[i] <= 2)
                per[1]++;
            if (score2Grade[i] > 2 && score2Grade[i] <= 3)
                per[2]++;
            if (score2Grade[i] > 3 && score2Grade[i] <= 4)
                per[3]++;
            if (score2Grade[i] > 4 && score2Grade[i] <= 5)
                per[4]++;
        }
        for (int i = 0; i < 5; i++){
            persentGrade[i] = float(per[i])
                / stuNum;
            cout << i << "~" << i + 1 << "比例为：" << persentGrade[i] << endl;
        }
    }
    float Average(int *stuScore){
        int sum = 0;
        for (int i = 0; i < stuNum; i++) // 求和
            sum += stuScore[i];
        return float(sum) / stuNum; // 得到平均值
    }
    float StandardDeviation(int *stuScore)
    {
        float sum = 0;
        float average = Average(stuScore);
        for (int i = 0; i < stuNum; i++) // 求和
            sum += pow(stuScore[i] - average, 2);
        return sqrt(sum / stuNum);
    }
};

void main(){
    MyScores t;
    cin >> t.stuNum;
    t.stuScore = new int[t.stuNum];
    t.score2Grade = new float[t.stuNum];
    t.persentGrade = new float[5];
    t.stuRandomScore(t.stuScore);
    cout << endl;
    t.Score2Grade(t.stuScore);
    cout << endl;
    t.PersentGrade(t.score2Grade);
    cout << endl;
    float average = t.Average(t.stuScore);
    cout << "平均值：" << average << endl;
    float sd = t.StandardDeviation(t.stuScore);
    cout << "标准差：" << sd << endl;
    system("pause");
}