Problems with linking inline functions in C++

Question

test2.h

#ifndef TEST2_H_INCLUDED
#define TEST2_H_INCLUDED
#include "test1.h"

inline int add(int,int);

#endif // TEST2_H_INCLUDED

test2.cpp

#include "test2.h"

inline int add(int a,int b){
    return a+b;
}

main.cpp

#include <iostream>
#include "test2.h"

int main()
{
    std::cout << add(1,2);
    return 0;
}

Eror:

warning: inline function add(int,int) used but never defined
undefined reference to add(int,int)
ld returned 1 exit status

But if I remove inline from the files, the code compiles and executes fine. What am I doing wrong?

Note: I have seen all the threads on stack overflow,although they were similar to my question, the answers could not solve my issue

Using the mingw compiler with Code Blocks

You probably need to read up on what inline means exactly in C++ (e.g.: en.cppreference.com/w/cpp/language/inline). You seem to be trying to get the compiler to inline the function at its usage, which is not what the keyword is for — UnholySheep
– UnholySheep, Commented Sep 25, 2020 at 10:12
@UnholySheep I am just learning about inline functions and following this page, so far I haven't done anything different — user14248283
– user14248283, Commented Sep 25, 2020 at 10:15
The page you linked to has the function declaration and definition merged into one. You have it separated, which you cannot do the way you are trying to — UnholySheep
– UnholySheep, Commented Sep 25, 2020 at 10:16

Allen Zhu · Accepted Answer · 2020-09-25 11:24:26Z

1

//test2.h
#ifndef TEST2_H_INCLUDED
#define TEST2_H_INCLUDED
#include "test1.h"

inline int add(int a,int b) {
    return a+b;
}

#endif // TEST2_H_INCLUDED

answered Sep 25, 2020 at 11:24

Allen Zhu

9007 silver badges15 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

SushiWaUmai · Accepted Answer · 2020-09-25 10:33:42Z

1

You have to define the inline function inside the header file, more info under https://stackoverflow.com/questions/5057021/why-are-c-inline-functions-in-the-header#:~:text=If%20you%20want%20to%20put,compiler%20cannot%20inline%20the%20function.

answered Sep 25, 2020 at 10:33

SushiWaUmai

3597 silver badges22 bronze badges

Collectives™ on Stack Overflow

Problems with linking inline functions in C++

test2.h

test2.cpp

main.cpp

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

test2.h

test2.cpp

main.cpp

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related