Question

我正在写一本GPA计算器。我在OR（||）函数中遇到问题，检查信用输入是否正确（如果不正确，则应再次询问）。此外，当成绩的输入是＆＃34; I＆＃34;或＆＃34; W＆＃34;程序不应该使用该信息（它不应该对它做任何事情）。谢谢你的帮助。这是代码：

    // Include Statements
#include <iostream>
using namespace std;

//Program to calculate GPA
int main()
{
    // Program made by Jose Luis Landivar
    // Fall 2016
    cout << ""<< endl;
    cout << "The following program will calculate your GPA "<< endl<<'\n';

    char grade;
    int g = 1;
    //variables for the algebraic operations needed
    int credit = 0;
    int totalcredit = 0;
    int ptotal = 0;
    double gpa, p = 1;
    double count = 1;
    double nclass;
    string coursename, coursenumber;


    cout << "Please enter the number of classes for the GPA calculator"<< endl;
        cin >> nclass;
    cout << ""<< endl;
    while (count <= nclass ) // While
    {
        //Information for the class
        cout << "Please enter the course name for the class # "<< count << endl;
            cin >> coursename;
        cout << "Please enter the course number for the class # "<< count << endl;
            cin >> coursenumber;

        //Getting grades and credits from user
        cout << "Enter the grade for the class # "<< count <<" (A,B,C,D,F,I,W)"<< endl;
            cin >> grade;
        if (grade == 'A' || grade == 'B' || grade == 'C' || grade == 'D' || grade == 'F' || grade == 'I' || grade == 'W')

        {

            // If for grades
            if (grade == 'A')
            {
                g = 4;
                cout << "Enter the number of credits for the class # "<< count <<" (1,2,3,4,5)"<< endl;
                    cin >> credit;
                cout << ""<< endl;
                if (credit == 5 || credit == 4 || credit == 3 || credit == 2 || credit == 1){
                    p = g * credit;
                    totalcredit = totalcredit + credit;
                    ptotal = ptotal + p;
                }
                else {cout << "Input is incorrect\n";
                }
            }


            if (grade == 'B')
            {
                g = 3;
                cout << "Enter the number of credits for the class # "<< count <<" (1,2,3,4,5)"<< endl;
                    cin >> credit;
                cout << ""<< endl;
                if (credit == 5 || credit == 4 || credit == 3 || credit == 2 || credit == 1){
                    p = g * credit;
                    totalcredit = totalcredit + credit;
                    ptotal = ptotal + p;
                }
                else {cout << "Input is incorrect\n";
                }
            }

            if (grade == 'C')
            {
                g = 2;
                cout << "Enter the number of credits for the class # "<< count <<" (1,2,3,4,5)"<< endl;
                    cin >> credit;
                cout << ""<< endl;
                if (credit == 5 || credit == 4 || credit == 3 || credit == 2 || credit == 1){
                    p = g * credit;
                    totalcredit = totalcredit + credit;
                    ptotal = ptotal + p;
                }
                else {cout << "Input is incorrect\n";
                }
            }

            if (grade == 'D')
            {
                g = 1;
                cout << "Enter the number of credits for the class # "<< count <<" (1,2,3,4,5)"<< endl;
                    cin >> credit;
                cout << ""<< endl;
                if (credit == 5 || credit == 4 || credit == 3 || credit == 2 || credit == 1){
                    p = g * credit;
                    totalcredit = totalcredit + credit;
                    ptotal = ptotal + p;
                }
                else {cout << "Input is incorrect\n";
                }
            }

            if (grade == 'F')
            {
                g = 0;
                cout << "Enter the number of credits for the class # "<< count <<" (1,2,3,4,5)"<< endl;
                    cin >> credit;
                cout << ""<< endl;
                if (credit == 5 || credit == 4 || credit == 3 || credit == 2 || credit == 1){
                    p = g * credit;
                    totalcredit = totalcredit + credit;
                    ptotal = ptotal + p;
                }
                else {cout << "Input is incorrect\n";
                }
            }

            count = count + 1;
        }

        else {cout << "Input is incorrect\n";
        }
    }
    //algebraic formulas
    gpa = ptotal/totalcredit;

    //output results
    cout << "Your total number of credits is: " << totalcredit << endl;
    cout << "Your GPA is: " << gpa << endl;

    if (grade == 'I')
    {
    }
    if (grade == 'W')
    {
    }
    return 0;
}

Answer 1

将int与char进行比较时要小心。例如：

int credit = 3;

// THIS WILL FAIL
if (credit == '3') {
}

3的int和'3'的char不相等。虽然您可以比较char和int，但它们没有相同的值。例如

cout << "Int : " << int(3) << std::endl;
cout << "Char: " << int('3') << std::endl;

给出输出：

Int : 3
Char: 51

你应该改变

的每一次出现

if (credit == '5' || credit == '4' || credit == '3' || credit == '2' || grade == '1'){
                                                                     // ^^^ is this suppose to be "credit"?

到

if (credit == 5 || credit == 4 || credit == 3 || credit == 2 || credit == 1){

<强>更新
请注意，当提供“I”或“W”时，您的代码实际上从不执行任何操作（除了增加课程count变量之外）。但是，当 EVERY 当然是“我”或“W”时（即所有课程都是（I）ncomplete或（W）ithdrawl）那么你的totalcredit变量将等于0给出你是'除以0'错误。变化

//algebraic formulas
gpa = ptotal/totalcredit;

到

if (totalcredit > 0) {
   gpa = ptotal/totalcredit;
} else {
   gpa = 0;
}

else语句可能不是必需的（gpa已经为零），但是当没有有效的信用来计算GPA时，它会明确显示你想要GPA的内容。

GPA计算器。 OR的问题并除以0

1 个答案: