好的，所以我必须编写一个程序，当用户输入"load filename"时，其中"filename"是您要打开的文件的象征（例如"input.txt"）。这将读入所有数据并存储学生的姓名，成绩和计算平均值。然后，用户可以输入"display filename"，其中将显示学生的姓氏，名字以及他们在出勤，家庭作业，项目，期中考试和期末考试中的所有分数。输入文件将始终具有相同的前5行，它们看起来像这样：
Attendance: 5
Midterm: 20
Final: 20
Homework: 15
Projects: 40
Henry, Patrick
Attendance: 12 15
Midterm: 80 100
Homework: 50 100
Homework: 60 100
Homework: 80 100
Project: 90 100
Project: 80 100
Project: 75 100
Final: 80 100
第一个数字是学生收到的，第二个是他们可能得分的数字。家庭作业和项目总是超过100分，但是你不知道每个人有多少。但是，您将拥有其他类别之一。最后一个类别总是最终的，可能会或可能不会被另一个学生跟随。学生人数不会超过100人。我写了这段代码：
int main()
{
int numStudents = 0;
int projCount = 0;
int hwCount = 0;
student students[100];
string command, filename;
cout << "What do you want to do?" << endl;
cin >> command;
ifstream in ;
cin >> filename;
string Attendance, Midterm, Final, Homework, Projects;
int A, M, F, H, P;
while (!in.fail())
{
if (command == "Load"
|| command == "load"
|| command == "l")
{
in .open(filename);
in >> Attendance >> A
>> Midterm >> M
>> Final >> F
>> Homework >> H
>> Projects >> P;
string lname, fname;
in.ignore(200, '\n');
getline(in, lname, ',');
getline(in, fname, '\n');
while (!in.fail())
{
string cat;
int score, possible;
in >> cat;
in >> score >> possible;
while (cat != "Final:")
{
students[numStudents].last = lname;
students[numStudents].first = fname;
if (cat == "Attendance:")
{
students[numStudents].attendpos = possible;
students[numStudents].attendgot = score;
students[numStudents].attgrade = (score * A) / possible;
}
else if (cat == "Midterm:")
{
students[numStudents].midpos = possible;
students[numStudents].midgot = score;
students[numStudents].midgrade = (score * M) / possible;
}
else if (cat == "Homework:")
{
students[numStudents].hw[hwCount] = score;
hwCount++;
students[numStudents].hwgrade = (score * H) / 100;
}
else if (cat == "Project:")
{
students[numStudents].proj[projCount] = score;
projCount++;
students[numStudents].projgrade = (score * P) / 100;
}
in >> cat; in >> score >> possible;
}
in >> score >> possible;
students[numStudents].finpos = possible;
students[numStudents].fingot = score;
students[numStudents].fingrade = (score * F) / possible;
students[numStudents].average = students[numStudents].fingrade + students[numStudents].hwgrade + students[numStudents].projgrade + students[numStudents].attgrade + students[numStudents].midgrade;
numStudents++; in .ignore(200, '\n');
getline(in, lname, ',');
getline(in, fname, '\n');
}
for (int i = 0; i < numStudents; i++)
{
cout << students[i].average << endl;
}
}
else if (command == "Display" || command == "display" || command == "d")
{
cout << "Displayed: " << filename << endl;
cout << "#Students:" << numStudents << endl;
cout << "Last Name" << " First Name" << " Attendance";
for (int i = 0; i < hwCount; i++)
{
cout << "HW" << i << " ";
}
for (int i = 0; i < projCount; i++)
{
cout << "Proj" << i << " ";
}
cout << " Midterm";
cout << " Final" << endl;
for (int i = 0; i < numStudents; i++)
{
cout << students[i].last << " " << students[i].first << " " << students[i].attendgot;
int j = 0;
while (j < numStudents)
{
for (int i = 0; i < hwCount; i++)
{
cout << students[j].hw[hwCount] << " ";
}
for (int i = 0; i < projCount; i++)
{
cout << students[i].proj[projCount] << " ";
}
j++;
}
cout << students[i].midgot << " " << students[i].fingot << " " << students[i].average << endl;
}
}
else if (command == "Sort" || command == "sort" || command == "s")
{
cout << "A" << endl;
}
else
{
cout << "I didn't recognize that" << endl; in >> command;
}
}
}
这是我的头文件：
struct student
{
string last;
string first;
double attgrade;
double midgrade;
double hwgrade;
double projgrade;
double fingrade;
int attendpos;
int attendgot;
int midpos;
int midgot;
int finpos;
int fingot;
int hw[20];
int proj[20];
double average;
};
然而，我遇到的问题是，在您输入"load filename"之后代码停止运行而我不知道原因。另外，我还没有完成排序部分所以不要担心其他if语句。我包含了所有必要的库。但是，为什么在输入第一个命令后程序会停止？
编辑： 除此之外，它还仅出于某种原因存储一个学生的信息。请帮帮我！
非常感谢任何帮助！
谢谢！
答案 0 :(得分：0)
我已经尝试过你的程序了。 我怀疑它只是没有打开所需的输入文件。 尝试在in.open之后添加以下内容（...
if(in.good())
{
cout << "file opened"<<endl;
}
else
{
cout << "file not opened"<<endl;
}
我使用msvc2008编译了以下内容...并使用调试器确认了您的预期程序行为。
// test1.cpp : Defines the entry point for the console application.
#include "stdafx.h"
#include <iostream>
#include <string>
#include <fstream>
using namespace std;
struct student
{
string last;
string first;
double attgrade;
double midgrade;
double hwgrade;
double projgrade;
double fingrade;
int attendpos;
int attendgot;
int midpos;
int midgot;
int finpos;
int fingot;
int hw[20];
int proj[20];
double average;
};
int main(int argc, char* argv[])
{
int numStudents = 0;
int projCount = 0;
int hwCount = 0;
student students[100];
string command, filename;
cout << "What do you want to do?" << endl;
cin >> command;
ifstream in ;
cin >> filename;
string Attendance, Midterm, Final, Homework, Projects;
int A, M, F, H, P;
while (! in .fail())
{
if (command == "Load" || command == "load" || command == "l")
{ in.open(filename.c_str());
if(in.good())
{
cout << "file opened"<<endl;
}
else
{
cout << "file opened"<<endl;
}
in >> Attendance ;
in >> A ;
in >> Midterm >> M >> Final >> F >> Homework >> H >> Projects >> P;
string lname, fname; in .ignore(200, '\n');
getline( in , lname, ',');
getline( in , fname, '\n');
while (! in .fail())
{
string cat;
int score, possible; in >> cat; in >> score >> possible;
while (cat != "Final:")
{
students[numStudents].last = lname;
students[numStudents].first = fname;
if (cat == "Attendance:")
{
students[numStudents].attendpos = possible;
students[numStudents].attendgot = score;
students[numStudents].attgrade = (score * A) / possible;
}
else if (cat == "Midterm:")
{
students[numStudents].midpos = possible;
students[numStudents].midgot = score;
students[numStudents].midgrade = (score * M) / possible;
}
else if (cat == "Homework:")
{
students[numStudents].hw[hwCount] = score;
hwCount++;
students[numStudents].hwgrade = (score * H) / 100;
}
else if (cat == "Project:")
{
students[numStudents].proj[projCount] = score;
projCount++;
students[numStudents].projgrade = (score * P) / 100;
} in >> cat; in >> score >> possible;
} in >> score >> possible;
students[numStudents].finpos = possible;
students[numStudents].fingot = score;
students[numStudents].fingrade = (score * F) / possible;
students[numStudents].average = students[numStudents].fingrade + students[numStudents].hwgrade + students[numStudents].projgrade + students[numStudents].attgrade + students[numStudents].midgrade;
numStudents++; in .ignore(200, '\n');
getline( in , lname, ',');
getline( in , fname, '\n');
}
for (int i = 0; i < numStudents; i++)
{
cout << students[i].average << endl;
}
}
else if (command == "Display" || command == "display" || command == "d")
{
cout << "Displayed: " << filename << endl;
cout << "#Students:" << numStudents << endl;
cout << "Last Name" << " First Name" << " Attendance";
for (int i = 0; i < hwCount; i++)
{
cout << "HW" << i << " ";
}
for (int i = 0; i < projCount; i++)
{
cout << "Proj" << i << " ";
}
cout << " Midterm";
cout << " Final" << endl;
for (int i = 0; i < numStudents; i++)
{
cout << students[i].last << " " << students[i].first << " " << students[i].attendgot;
int j = 0;
while (j < numStudents)
{
for (int i = 0; i < hwCount; i++)
{
cout << students[j].hw[hwCount] << " ";
}
for (int i = 0; i < projCount; i++)
{
cout << students[i].proj[projCount] << " ";
}
j++;
}
cout << students[i].midgot << " " << students[i].fingot << " " << students[i].average << endl;
}
}
else if (command == "Sort" || command == "sort" || command == "s")
{
cout << "A" << endl;
}
else
{
cout << "I didn't recognize that" << endl; in >> command;
}
}
}