Code Blocks Separate Compilation Error

[SerRing]

So I am in the process of learning C++ and currently learning separate compilation. I am able to include the header file in the source file but I am unable to retrieve a structure deceleration from it.

main.cpp

#include <iostream>
#include "Testing.h"
using namespace std;
int main()
{
    box wood;
}

Testing.h

#define Testing_H
#ifndef Testing_H

struct box
{
    int height;
    int width;
};
#endif 

"'box' was not declared in this scope" Was the error I received

Here's an image in case that helps.
https://ibb.co/mdLFka

[gunnerfunner]

the pre-processor directives should be in this order:

#ifndef Testing_H
#define Testing_H 

[SerRing]

It works, thank you very much.