Lnk1120

Code:

---

// streams.cpp : Defines the entry point for the console application.
//


#include "stdafx.h"
#include <iostream>


#include <fstream>
#include<conio.h>
using namespace std;
class Student
{
    private:
    int number;
    char name[50];
    float gpa;


    public:
    Student (int n,const char *s, float g);
    void save(ofstream& of);
    void load(ifstream& inf);
};


int main()
{
  Student me(11321, "Myself", 4.3);
  ofstream myfile;
  ifstream myf;
  myfile.open("silly.txt");
  me.load(myf);
  me.save(myfile);
  myfile.close();
  getch();
  return 0;
}


void Student::save(ofstream& of)
{
  of.write((char*)&number, sizeof(number));
  of.write((char*)name, sizeof(name));
  of.write((char*)&gpa, sizeof(gpa));
}


void Student::load(ifstream& inf)
{
  inf.read((char*)&number, sizeof(number));
  inf.read((char*)name, sizeof(name));
  inf.read((char*)&gpa, sizeof(gpa));
}

---

On compilation it gives:
1>streams.obj : error LNK2019: unresolved external symbol "public: __thiscall Student::Student(int,char const *,float)" (??0Student@@QAE@HPBDM@Z) referenced in function _main
1>c:\users\javed\documents\visual studio 2010\Projects\streams\Debug\streams.exe : fatal error LNK1120: 1 unresolved externals
Although i followed what is suggested here:

> Student (int n,const char *s, float g);
You also need to implement this constructor as well.

As in

Code:

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Student::Student (int n,const char *s, float g) {
  // do something
}

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You shouldn't use char arrays. Use std::string. Otherwise you are in for a world of hurt (e.g. buffer overflow possibility, etc).