C++ - Reference variables

C++ - Reference variables
in the Thinking in C++ (p. 151)
"Pointers work roughly the same in C and in C++, but C++ adds an additional way to pass an address into a function. This is pass-by-reference and it exists in several other programming languages so it was not a C++ invention."

int a = 0;
int &ref = a;

https://www.learncpp.com/cpp-tutorial/611-references/

Pointer vs. Reference
1. Pointers are a superset, references are a subset.
2. References must be initialized when created.
3. References can not be reassigned.

#pragma once vs. #ifndef

#pragma once is NOT standard
But #ifndef is standard
#ifndef XXX_YYYY
#define XXX_YYYY


#endif // XXX_YYYY

In the compile-time #pragma once is faster.

https://stackoverflow.com/questions/1143936/pragma-once-vs-include-guards
https://beesbuzz.biz/code/1473-pragma-once-vs-ifndef-define

[VS Code] enable define in C & C++

Setting Visual Studio Code

c_cpp_properties.json
ctrl+shift+p
>C/C++:Edit Configuration (JSON)

Make c_cpp_properties.json in .vscode folder, and
 - Updated c_cpp_properties.json syntax

"configurations": [
    {
        "defines": [
            "WIN32",
        ],
        // ...
    }
],