C ++ believes that "<<" is not a member of the class, but it is

Question

I need to write a simple log class that will write output to a file.

I want it to work with operator overloading, so I can do this:

MyLog log("C:\\log.txt");
log<<"Message";

But Visual C ++ tells me: "error C2039: '<<: is not a member of" MyLog "

I do not know what I am doing wrong.

Here is the code:

Mylog.h

#pragma once
#include <iostream>
#include <conio.h>
#include <fstream>
using namespace std;

class MyLog
{
private:
    ofstream logfile;
public:
    MyLog(char* filename);
    friend MyLog& operator<<(MyLog& l,char*msg);
};

Mylog.cpp

#include "MyLog.h"

MyLog::MyLog(char* filename)
{
    logfile.open(filename);
}

MyLog& MyLog::operator<<(MyLog& l,char*msg)
{
    cout<<msg;
    return l;
}

Does anyone know what is wrong?

Answer 1

You declared a free function MyLog& operator<<(MyLog& l,char* msg)as a friendclass MyLog. It is not a member of the class itself, so your function definition should begin with this:

MyLog& operator<<(MyLog& l,char* msg)
{
   //...

Answer 2

Visual ++ , operator<< MyLog. - :

class MyLog {
    // ...

public:
    MyLog& operator<<(int i);
}

MyLog& MyLog::operator<<(int i) {
    cout << i;
    return *this;
}

Answer 3

char *:

< < "";

int:

MyLog & MyLog:: operator < (MyLog & l, int i)

, " "

Answer 4

<< int, char *.

char *:

MyLog& operator<<(MyLog& l,char* msg);

, friend?

Answer 5

friend MyLog& operator<<(MyLog& l,int i);

MyLog& operator<<(MyLog& l,int i);

Answer 6

< < , MyLog. :

MyLog & < (MyLog & l, int i) {    <