function … has already a body & function template has already been defined

Question

I have this header file:

Utility.h:

#pragma once

#include 
#include 
#include 
#includ         


        

Answer 1

There are main two problems:

• You have placed intended header code in a ".cpp" file, which your IDE by default will treat as a main source code file (translation unit).

• You are including non-inline function definitions (the class member functions) in the global namespace in a header. When that header is included in two or more translation units you will get a One Definition Rule (ODR) violation. In practice the linker will complain.

To fix this:

• Change the filename extension from ".cpp" to e.g. ".hpp" or just plain ".h". It is code intended for header file use. The filename extension should reflect that, instead of misleading.

• Declare the functions inline, or place definitions within the class definition.

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In other news, possibly one of the clocks, from the standard library, will serve your purpose so that you don't have to include in a header. It does drag in a zillion unreasonable macros. Including, by default, lowercase min and max macros, so this code is very ungood as given.