Question

我的主题可能令人困惑，这是我在C ++中的代码，如何在程序结束时显示每个年级的学生人数的摘要，可以有任何人帮吗？

#include <iostream>
#include <fstream>
#include <time.h> 
#include <iomanip>
#include <algorithm>    
#include <vector>       

/* run this program using the console pauser or add your own getch, system("pause") or input loop */
using namespace std;
int main(int argc, char** argv) {

这是我想要的输出，任何人都可以帮忙吗？

这是我的实际输出 [节目输出] [1]

编辑：感谢你们的回复，因为我现在正在学习所需的编程课程，虽然我之前已经完成了100％的材料，但我还是用C ++完成了所有这些，所以我的语法还不是很好，我们仅通过讲座中讨论过的函数/循环/方法来讲述，看起来我还需要付出更多努力。

Answer 1

我不确定我是否正确理解了这个问题，但是每次你确定if-else-cascade中的等级然后std :: cout在while循环之后的结果时你可以增加指定的计数器。

Answer 2

您可以尝试Wum建议的内容，因此代码可能如下所示：

#include <iostream>
#include <fstream>
#include <time.h>
#include <iomanip>
#include <algorithm>
#include <vector>

/* run this program using the console pauser or add your own getch, system("pause") or input loop */

using namespace std;

int main(int argc, char** argv) {
    char date[9];
    ifstream in;
    ofstream out;

    string name;
    char grade;
    double asg1, asg2, test, quiz, exam, coursework, overallScore, numbergrade;
    int numStudentsA = 0;
    int numStudentsB = 0;
    int numStudentsC = 0;
    int numStudentsD = 0;
    int numStudentsF = 0;

    in.open("Student.txt");
    out.open("Result.txt");

    in >> name >> asg1 >> asg2 >> test >> quiz >> exam;

    //to keep reading the data in input file
    while (!in.eof()) {
        coursework = asg1 + asg2 + test + quiz;
        overallScore = coursework + exam;

        if (overallScore >= 70 ) {
            grade = 'A'; 
            numStudentsA++;
        }
        else if (overallScore >= 60) {
            grade = 'B'; 
            numStudentsB++;
        }
        else if (overallScore >= 50) {
            grade = 'C'; 
            numStudentsC++;
        }
        else if (overallScore >= 40) {
            grade = 'D'; 
            numStudentsD++;
        }
        else if (overallScore >= 0) {
            grade =  'F'; 
            numStudentsF++;
        }// grade

        out << left << setw(15) << name ;
        out << left << setw(3) <<coursework ; //coursework
        out << left << setw(3) << exam ; //exam
        out << left << setw(4) << overallScore ; //overall score
        out << grade ;
        out << endl;

        in >> name >> asg1 >> asg2 >> test >> quiz >> exam;
    }

    cout << "Result Summary   Date: " << date << endl;
    cout << "Subeject: Programming Methodology" << endl;
    cout << "Grade" << setw(10) << "Student" << endl;
    cout << "A" << setw(10) << numStudentsA << endl;
    cout << "B" << setw(10) << numStudentsB << endl;
    cout << "C" << setw(10) << numStudentsC << endl;
    cout << "D" << setw(10) << numStudentsD << endl;
    cout << "F" << setw(10) << numStudentsF << endl;
    cout << "Total Student = 10" << endl;

    return 0;
}

我对你的代码应用了一些缩进，尝试使用单一的编码风格。另外，您应该了解为什么不建议使用eof()。

Answer 3

使用数组来计算每个年级的学生人数，并在最后打印出数组。[寻找内联评论]

使用枚举索引数组以便于阅读。

您可以使用地图而不是数组是其中一个建议。

在上述情况下，eof是正常的，第一次读取在while循环之外，然后检查在开始时完成。此后的读取也在while结束时，因此程序将在读取后立即循环回来以检查eof条件并退出（不处理空缓冲区）。

以下代码检查while (in>>name>>asg1>>asg2>>test>>quiz>>exam)

#include <iostream>
#include <fstream>
#include <time.h>
#include <iomanip>
#include <algorithm>
#include <vector>

enum { GRADE_A = 0 , GRADE_B = 1, GRADE_C = 2 , GRADE_D = 3 ,GRADE_F = 4}; // use an enum to index into the array for each grade 

/* run this program using the console pauser or add your own getch, system("pause") or input loop */
using namespace std;
int main(int argc, char** argv) {


   char date[9];
    _strdate(date);
    ifstream in;
    ofstream out;
     int grades[5]; // to store the grades count


    string name;
    char grade;
    double asg1,asg2,test,quiz,exam,coursework,overallScore,numbergrade;




    in.open("Student.txt");
    out.open("Result.txt");


     grades[GRADE_A] = 0 ; grades[GRADE_B] = 0 ; grades[GRADE_C] = 0 ; grades[GRADE_D] = 0 ; grades[GRADE_F] = 0 ; // initialize array 

   while (in>>name>>asg1>>asg2>>test>>quiz>>exam)       //to keep reading the data in input file
 {



    coursework = asg1 + asg2 + test + quiz;
    overallScore = coursework + exam;


    if (overallScore >= 70 )
    {grade = 'A'  ;grades[GRADE_A]++;} // increment count for each grade 

    else if (overallScore >= 60)
    {grade = 'B'  ;grades[GRADE_B]++;}

    else if (overallScore >= 50)
    {grade = 'C'  ;grades[GRADE_C]++;}

    else if (overallScore >= 40)
    {grade = 'D' ;grades[GRADE_D]++;}

    else if (overallScore >= 0)
    {grade =  'F'  ;grades[GRADE_F]++;};   // grade



    out<< left << setw(15) << name ;
    out<< left << setw(3) <<coursework ; //coursework
    out<< left << setw(3) << exam ; //exam
    out<< left << setw(4) << overallScore ; //overall score
    out<< grade ;
    out<< endl;


}
cout<<"Result Summary   Date: " << date << endl;
cout<<"Subeject: Programming Methodology"<<endl;
cout<< "Grade"<< setw(10) << "Student" <<endl;
cout<< "A" <<setw(10)<<grades[GRADE_A]<<endl; // output grade count
cout<< "B" <<setw(10)<<grades[GRADE_B]<<endl;
cout<< "C" <<setw(10)<<grades[GRADE_C]<<endl;
cout<< "D" <<setw(10)<<grades[GRADE_D]<<endl;
cout<< "F" <<setw(10)<<grades[GRADE_F]<<endl;
cout<<setw(0)<<endl;
cout<<"Total Student = 10"<<endl;
//At the end of the program, display the summary of number of student count for each Grade

如何使它成为可能

3 个答案: