谢谢大家,该程序的输出是固定的。除了studentNumber。我读到的评论是我从来没有给它定值,这让我感到困惑。
void process_file(ifstream& input)
{
int thisStudent = 0;
StudentRecord student = StudentRecord();
while (thisStudent++ < CLASS_SIZE)
{
student.input(input, thisStudent);
student.computeGrade();
student.output();
}
}
会不会将studentNumber设置为等于0,然后在每次循环中添加+1。
// Author:
// Assignment 8
#include <iostream>
#include <fstream>
#include <iomanip>
using namespace std;
ofstream outputfile("output.txt");
const int MAX_FILE_NAME = 35;
const int CLASS_SIZE = 5;
class StudentRecord
{
public:
void input( ifstream& input,int studentid);
void computeGrade();
void output();
private:
int studentNumber;
double exam1;
double exam2;
double exam3;
double exam4;
double average;
char grade;
};
void open_input(ifstream& input, char name[]);
void process_file(ifstream& input);
int main()
{ char again;
char file_name[MAX_FILE_NAME + 1];
ifstream input_numbers;
cout << "This program can calculate the exam average and grade for\n"
<< "each student.\n" << endl;
system("pause");
do
{
system("cls");
open_input(input_numbers, file_name);
process_file(input_numbers);
input_numbers.close();
cout << "\nDo you want to process another file (Y/N)? ";
cin >> again;
cin.ignore(256, '\n');
} while ( again == 'y' || again == 'Y');
cout << "\nEnd of Program!" << endl;
outputfile << "\n\nThanks for using GradeCalc!\f";
outputfile.close();
return 0;
}
void process_file(ifstream& input)
{
int thisStudent = 0;
StudentRecord student = StudentRecord();
while (thisStudent++ < CLASS_SIZE)
{
student.input(input, thisStudent);
student.computeGrade();
student.output();
}
}
void open_input(ifstream& input, char name[])
{ int count = 0;
do
{ count++;
if (count != 1)
{ cout << "\n\aInvalid file name or file does not exist. Please try again."
<< endl;
}
cout << "\nEnter the input file name (maximum of " << MAX_FILE_NAME
<< " characters please)\n:> ";
cin.get(name, MAX_FILE_NAME + 1);
cin.ignore(256, '\n');
input.clear();
input.open(name,ios_base::in);
} while (input.fail() );
}
void StudentRecord::input(ifstream& input, int studentid)
{
input >> exam1 >> exam2 >> exam3 >> exam4;
}
void StudentRecord::computeGrade()
{
average = (exam1 + exam2 + exam3 + exam4) / 4 ;
if (average >= 90)
grade = 'A';
else if (average >= 80)
grade = 'B';
else if (average >= 70)
grade = 'C';
else if (average >= 60)
grade = 'D';
else if (average < 60)
grade = 'F';
}
void StudentRecord::output()
{
cout << "\n\nThe record for student number:" << setw(8) << studentNumber << endl;
cout << "The exam grades are:" << setw(8) << exam1 << exam2 << exam3 << exam4 << endl;
cout << "The numeric average is:" << setw(8) << average << endl;
cout << "and the letter grade assigned is:" << setw(8) << grade << endl;
}
最佳答案
好吧,studentNumber是垃圾,因为您从未在其中输入任何值。因此,该位置上已经发生了任何事情。
考试成绩打印错了,因为C ++中的逗号没有按照您的想象做,这也是为什么在其中加上endl;
会导致错误的原因。
我将让您自己进行格式化。您应该考虑阅读输出或至少进行一些反复试验。