菜鸟 C++ 我不退出理解函数，尤其是如何将读取的文件传递到函数中的结构中

Question

#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
#include <vector>
#include <cstdlib>

using namespace std;


struct Student{
    string name, status;
    double grade1, grade2, 
           grade3, average;
};

string getInputFileName();
string getOutputFileName();
void readStudents(vector<Student>, string);
void writeStudents(vector<Student>, string);

int main(){

    vector<Student> students;
    string inputFileName, outputFileName;

    inputFileName = getInputFileName();
    outputFileName = getOutputFileName();

    readStudents(students, inputFileName);
    writeStudents(students, outputFileName);

    system("pause");
    return 0;
}

string getInputFileName(void){

    string getLocation;
    cout << "Please type the location of the file"
         << " you would like to open." << endl
         << ">>";
    cin  >> getLocation;


    return getLocation;

}

string getOutputFileName(void){


    string writeLocation;
    cout << "Please type the location of the file"
         << " you would like to write to." << endl
             << ">>";
    cin  >> writeLocation;


    return writeLocation;


}

void readStudents(vector<struct Student> inputFileName){
    struct Student{
    string name, status;
    double grade1, grade2, 
       grade3, average;
    };
    vector<Student> students;
    string name;
    double grade1, grade2, grade3;
    ifstream inFile;
    inFile.open(getInputFileName());

    while(!inFile.eof()){
            inFile >> name >> grade1 >> grade2 >> grade3;
    }
}
//write from input file 
void writeStudents(vector<struct Student> outputFileName){

    struct Student{
    string name, status;
    double grade1, grade2, 
       grade3, average;
    };
    vector<Student> students;
    string name;
    double grade1, grade2, grade3;
    ofstream outFile;
    outFile.open(getInputFileName());

    while(!outFile.eof()){
            outFile << name << grade1 << grade2 << grade3;
    }
}

The errors I'm getting are uninitialized variables in the 4th function. I don't know why. probably because I'm not inputting the info correctly. I want to be able to read from the user input file location and write to the user specified location while using the structure data type. Im stuck at the moment.

Answer 1

The errors I'm getting are uninitialized variables in the 4th function...

I guess it's your writeStudents function.

There are a few things wrong.

---

This function has a declaration and a definition. These should be compatible, they aren't quite so:

void writeStudents(vector<Student>, string); // declaration
void writeStudents(vector<struct Student> outputFileName) {...} //definition

The declaration says that the functions gets 2 parameters; the definition should state the same; and it should also give names to these parameters. Here is an example definition:

void writeStudents(vector<Student> parameter1, string parameter2) {...}

There are names better than parameter1 and parameter2 - you already have these better names elsewhere in your code:

void writeStudents(vector<Student> students, string outputFileName) {...}
// equivalent definition; works the same way but easier to read

---

There is much useless and confusing code in your writeStudents function:

struct Student{
string name, status;
double grade1, grade2, 
   grade3, average;
};
vector<Student> students;
string name;
double grade1, grade2, grade3;

I guess you copied it from somewhere by mistake; the compiler tried its best to make some sense of it, but probably got confused. Just delete this code.

---

The rest should be easy.