[SOLVED] C++ Structures, file does not compile, vector array has issues

Issue

I do not understand what is wrong but it seems like the problem lies with the vector, but after searching on the internet I could not solve this issue.

The error from the compiler looks like this:

main.cpp:25:21: error: expected primary-expression before ‘&’ token
   25 |     getdata(student &s,file);
      |                     ^
main.cpp:26:23: error: expected primary-expression before ‘&’ token
   26 |     printdata(student &s,file);
      |                       ^
main.cpp: In function ‘void getdata(student&, std::fstream)’:
main.cpp:36:15: error: no match for ‘operator[]’ (operand types are ‘student’ and ‘int’)
   36 |         cin>>s[i].name;
      |               ^
main.cpp:38:15: error: no match for ‘operator[]’ (operand types are ‘student’ and ‘int’)
   38 |         cin>>s[i].sno;
      |               ^
main.cpp:40:15: error: no match for ‘operator[]’ (operand types are ‘student’ and ‘int’)
   40 |         cin>>s[i].mark;
      |               ^
main.cpp:44:34: error: no match for ‘operator[]’ (operand types are ‘student’ and ‘int’)
   44 |         file<<"Student name: "<<s[i].name<<endl;
      |                                  ^
main.cpp:45:36: error: no match for ‘operator[]’ (operand types are ‘student’ and ‘int’)
   45 |         file<<"Student number: "<<s[i].snum<<endl;
      |                                    ^
main.cpp:46:33: error: no match for ‘operator[]’ (operand types are ‘student’ and ‘int’)
   46 |         file<<"term mark:   "<<s[i].mark<<endl;
      |                                 ^

#include <iostream>
#include <fstream>
#include <vector>
using namespace std;

struct student
{
    string name;
    int snum;
    double mark;
};

void getdata(student &s,fstream file);
void printdata(student &s,fstream file);

int main ()
{
    fstream file;
    int number;
    vector <student> s(3);

    cout<<"Enter number of students to account for: "<<endl;
    cin>>number;
    
    getdata(student &s,file);
    printdata(student &s,file);

}

void getdata(student &s, fstream file)
{
    file.open("Students.txt",ios::out);
    for(int i=0; i<3; i++)
    {
        cout<<"Enter your name: "<<endl;
        cin>>s[i].name;
        cout<<"Enter your student number: "<<endl;
        cin>>s[i].sno;
        cout<<"Enter your term mark: "<<endl;
        cin>>s[i].mark;
        cout<<endl;
        
        file<<"----------------------"<<endl;
        file<<"Student name: "<<s[i].name<<endl;
        file<<"Student number: "<<s[i].snum<<endl;
        file<<"term mark:   "<<s[i].mark<<endl;
        file<<"----------------------"<<endl;
        
    }
    file.close();
}

void printdata(student &s, fstream file)
{
    file.open("Students.txt",ios::in);
    string read;
    while(getline(cin,read))
    {
        cout<<read<<endl;
    }
    file.close();
}

Solution

These are not valid function calls:

getdata(student &s,file);
printdata(student &s,file);

They should be:

getdata(s,file);
printdata(s,file);

That will cause other errors because your functions clearly expect a vector<student>, but only take a student.

You also cannot pass fstream objects by value. They must be references.

Change your function parameter lists to look like this:

void getdata(vector<student> &s, fstream &file);
void printdata(vector<student> &s, fstream &file);

There’s also a typo with the member .sno which you meant .snum

Fix all this and your program will compile, then you can at least start debugging it to see if it even works.

Answered By – paddy

Answer Checked By – David Goodson (BugsFixing Volunteer)