Question

所以我有这个do-while循环，它应该重复询问你是否要为学生输入信息，如果你按y并通过input（）函数输入info，则数据存储在向量中。如果按q，程序应该打印向量中包含的信息并退出循环。

由于某种原因，循环完全为您输入的第一个和第二个学生执行。然后，而不是重复循环询问您是否要进入第三个学生，它似乎只是执行input（）函数。它不会问你'输入y继续或q退出'，你输入的任何学生信息似乎都没有存储。它在执行完整循环和输入（）函数之间间歇性地改变。我想知道是否有人知道为什么会这样，以及我可以做些什么来解决它。

干杯

#include <iostream>
#include <iomanip>
#include <cmath>
#include <cstring>
#include <string>
#include <vector>

using namespace std;

const int NO_OF_TEST = 4;

struct studentType
{
    string studentID;
    string firstName;
    string lastName;
    string subjectName;
    string courseGrade;

    int arrayMarks[4];

    double avgMarks;
};

studentType input();
double calculate_avg(int marks[],int NO_OF_TEST); // returns the average mark
string calculate_grade (double avgMark); // returns the grade 

void main()
{
    unsigned int n=0; // no. of student
    vector<studentType> vec; // vector to store student info
    studentType s;

    char response;
    do
    {
        cout << "\nEnter y to continue or q to quit... ";
        cin >> response;
        if (response == 'y')
        {
            n++;
            for(size_t i=0; i<n; ++i)
            {
                s = input();
                vec.push_back(s);
            }
        }

        else if (response == 'q')
        {
            for (unsigned int y=0; y<n; y++)
            {
                cout << "\nFirst name: " << vec[y].firstName;
                cout << "\nLast name: " << vec[y].lastName;
                cout << "\nStudent ID: " << vec[y].studentID;
                cout << "\nSubject name: " << vec[y].subjectName;
                cout << "\nAverage mark: " << vec[y].avgMarks;
                cout << "\nCourse grade: " << vec[y].courseGrade << endl << endl;
            }
        }
    }
    while(response!='q');
}

studentType input()
{   
    studentType newStudent;

    cout << "\nPlease enter student information:\n";

    cout << "\nFirst Name: ";
    cin >> newStudent.firstName;

    cout << "\nLast Name: ";
    cin >> newStudent.lastName;

    cout << "\nStudent ID: ";
    cin >> newStudent.studentID;

    cout << "\nSubject Name: ";
    cin >> newStudent.subjectName;

    for (int x=0; x<NO_OF_TEST; x++)
    {   cout << "\nTest " << x+1 << " mark: ";
        cin >> newStudent.arrayMarks[x];
    }

    newStudent.avgMarks = calculate_avg(newStudent.arrayMarks,NO_OF_TEST );
    newStudent.courseGrade = calculate_grade (newStudent.avgMarks);

    return newStudent;
}

double calculate_avg(int marks[], int NO_OF_TEST)
{
     double sum=0;

     for( int i=0; i<NO_OF_TEST; i++)
     {
         sum = sum+ marks[i];
     }

     return sum/NO_OF_TEST;

}


string calculate_grade (double avgMark)
{
    string grade= "";

    if (avgMark<50)
    {
        grade = "Fail";
    }

    else if (avgMark<65)
    {
        grade = "Pass";
    }

    else if (avgMark<75)
    {
        grade = "Credit";
    }       

    else if (avgMark<85)
    {
        grade = "Distinction";
    }

    else
    {
        grade = "High Distinction";
    }

    return grade;
}

Answer 1

我认为这段代码可以做到：

        n++;
        for(size_t i=0; i<n; ++i)
        {
            s = input();
            vec.push_back(s);
        }

第二次询问你们两个学生，第三次是三个学生，等等。

所以，做吧

        vec.push_back(input());

Do-while循环只在C ++中感觉它时执行？

1 个答案: