将接口与实现分开不起作用 C++

Question

Hey i was trying to use Separating interface from implementation but got error. Not understanding what's wrong. Here's my program here's the error image

#include<iostream>
#include"name.h"
using namespace std;
int main()
{
    int x,y;
    cin>>x>>y;
    name n1(x,y);
    n1.getdata(x,y);
    n1.showdata();
}

now here's the created header file

#include<iostream>
using namespace std;
class name{
private:
    int a,b;
public:
    name(int x, int y);
    void getdata(int x, int y);
    int showdata();
};

& here's the next part of class

#include"name.h"
using namespace std;
name::name(int x, int y)
{
    a=0;
    b=0;
}
void name::getdata(int x,int y)
{
    a=x;
    b=y;
}
void name::showdata()
{
    cout<<a+b;
}

Answer 1

There are many problems with your code. It looks like the best advice in this situation would be to read a good C++ book .

When this is out of the way, here's the short-list of problems in the severity-descending order:

• name::showdata() declaration signature does not match difinitioin: int showdata() vs. void showdata()
• header misses an include guard
• using namespace in a header is a code smell 99 times out of 100
• header does not need to include <iostream> , it would suffice to include it in implementation file, where it's actually used.

By looking at undefined references you are getting, I would also guess that name.cpp is not build.

I fixed some of the mentioned points to just make it build: Live Demo