【发布时间】：2019-07-15 19:41:10
【问题描述】：
对不起，如果这是一个愚蠢的问题，我是菜鸟。
我正在使用函数将包含学生信息的文件 (readStudentRecord) 读取到对象数组中，然后使用另一个函数 (displayAllStudents) 打印出此信息。问题是我的程序只是打印垃圾数据，所以我认为我的做法是错误的。
我是 OOP 的新手，我仍然不清楚一切应该如何与类和不同的规范/实现文件进行交互，因此非常感谢任何帮助。
编辑：
经过一些修改，我现在输出的是 0 而不是垃圾。我相信问题出在我的 ID 变量上，出于某种原因，我的文件没有读入我不明白的内容。导致输出0。否则我的文件读取成功。
This is my input file and desired output
ID CLA OLA Quiz Homework Exam Bonus Total FinalGrade
c088801 10 15 4 15 56 5
c088802 9 12 2 11 46 2
c088803 8 10 3 12 50 1
c088804 5 5 3 10 53 3
c088805 3 11 1 10 45 0
c088806 8 14 2 11 40 -1
c088807 4 12 2 12 48 -2
c088808 10 10 3 11 36 0
c088809 8 8 3 11 39 0
c088810 6 9 4 9 47 3
c088811 8 7 3 13 41 3
c088812 4 11 3 11 37 1
c088813 9 15 2 8 50 2
c088814 8 12 2 10 48 4
c088815 6 8 1 7 45 1
c088816 7 7 2 6 51 2
c088817 8 9 2 12 38 2
Student.h and Roster.h file
#ifndef STUDENT_H
#define STUDENT_H
#include <string>
#include <stdexcept>
class Student
{
public:
enum ScoreType {CLA, OLA, QUIZ, HOMEWORK, EXAM, BONUS};
static const int CATEGORY_NUM = BONUS - CLA + 1;
Student(void);
//Accessor & mutator of m_id
std::string getID(void) const;
void setID(std::string) ;
//Accessor and mutator of m_score
void changeScore(const ScoreType, const int);
int getScore(const ScoreType) const;
private:
std::string m_id; // Student ID
int m_score[CATEGORY_NUM];
};
#endif
#ifndef ROSTER_H
#define ROSTER_H
#include <string>
#include <stdexcept>
#include "Student.h"
class Roster
{
public:
Roster(std::string courseName);
void readStudentRecord();
void displayAllStudents();
private:
static const int MAX_NUM = 25; //Max student # in class
std::string m_courseName; //Name of course
int m_studentNum; //Actual student #
Student m_students[MAX_NUM]; //Array of student objects
};
#endif
Student.cpp file
#include "Student.h"
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
//Student constructor
Student::Student(void) {
}
//Accesor and Mutator of m_id
string Student::getID(void) const {
return m_id;
}
void Student::setID(string ID) {
m_id = ID;
}
//Accessor and Mutator of m_score
int Student::getScore(const ScoreType st) const {
return m_score[st];
}
void Student::changeScore(const ScoreType st, const int score) {
m_score[st] = score;
}
Roster.cpp file
#include "Roster.h"
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
//Roster constructor
Roster::Roster(string courseName){
m_courseName = courseName;
m_studentNum = 0;
}
//Function will read from input file and store data into an array of objects.
void Roster::readStudentRecord() {
Student m_students[MAX_NUM];
string ID, line;
int CLA, OLA, Quiz, Homework, Exam, Bonus;
ifstream inFile; //Reads input file
inFile.open("point.dat");
getline(inFile, line); //Skips first line of file
int i = 0;
inFile >> ID >> CLA >> OLA >> Quiz >> Homework >> Exam >> Bonus;
while (inFile) {
inFile >> ID >> CLA >> OLA >> Quiz >> Homework >> Exam >> Bonus;
i++;
}
for (int i = 0; i < MAX_NUM; i++) {
m_students[i].setID(ID);
m_students[i].changeScore(Student::CLA, CLA);
m_students[i].changeScore(Student::OLA, OLA);
m_students[i].changeScore(Student::QUIZ, Quiz);
m_students[i].changeScore(Student::HOMEWORK, Homework);
m_students[i].changeScore(Student::EXAM, Exam);
m_students[i].changeScore(Student::BONUS, Bonus);
//>> m_students[i].total >> m_students[i].letterGrade;
}
cout << endl;
cout << "file read sucessfully" << endl;
inFile.close();
}
//Function will display every student's information from roster.
void Roster::displayAllStudents() {
cout << endl;
cout << "All student information is given below:" << endl;
cout << endl;
cout << " ID CLA OLA Quiz Homework Exam Bonus Total" <<
endl;
for (int i = 0; i < MAX_NUM; i++) {
cout << m_students[i].getID() << " " <<
m_students[i].getScore(Student::CLA) << " " <<
m_students[i].getScore(Student::OLA) << " " <<
m_students[i].getScore(Student::QUIZ) << " " <<
m_students[i].getScore(Student::HOMEWORK) << " " <<
m_students[i].getScore(Student::EXAM) << " " <<
m_students[i].getScore(Student::BONUS) << " " << endl;
}
}
main.cpp
#include "Student.h"
#include "Roster.h"
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main() {
Roster obj("CSCI");
obj.readStudentRecord();
obj.displayAllStudents();
system("pause");
return 0;
}
My output
file read sucessfully
All student information is given below:
ID CLA OLA Quiz Homework Exam Bonus Total
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
Press any key to continue . . .
【问题讨论】：
-
-858993460 转换为十六进制为 CCCCCCCC，这是正常的运气，尤其是连续 150 次。 The program is trying to tell you something.
-
我在
readStudentRecord中看不到任何文件可以确保任何文件读取成功或文件甚至已打开。 -
我确保该文件是可打开的并运行了您的代码。它运行并输出合理的结果。你有一个问题，因为
for (int i = 0; i < MAX_NUM; i++)一直在读取文件末尾，但是添加了一些检查以确保文件正在打开，将输入文件放在正确的位置，这个错误应该被清除。 -
始终在您打开文件时检查它是否成功。我赌一分钱你没能打开你的文件。当您确认我们可以讨论文件打开失败的原因时。
-
再来一次？ stackoverflow.com/questions/57007825/… 。代码大大改进。但是读取文件似乎仍然是一个问题。请始终检查您的 ifstream 的状态。任何失败位设置？你读了 25 行。如果行数少了怎么办？不要使用 C 风格的数组！
标签： c++ arrays class object io