Thread: 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:

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

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