Question

Is it possible to put the variable declarations in an external function? After reading from Wikipedia that:

an inline function is a function upon which the compiler has been requested to perform inline expansion. In other words, the programmer has requested that the compiler insert the complete body of the function in every place that the function is called, rather than generating code to call the function in the one place it is defined.

I hypothesized that the following might work. It did not take long for the compiler to slap my fingers 🙁

inline void declaration(){
    int a;
}

int main(){
    declaration();
    a=2;
    return 0;
}

Answer 1

This may not be how it is done but if you want a basic idea of how you can think about what happens when you inline a function.

Imagine the compiler turning your code into something like this, then you see why it will not work.

int main(){
    {
        int a;
    }
    a=2;
    return 0;
}

The call to declaration() is replaced by the contents of the function including brackets, thus int a; is declared in an inner scope and is not visible in the main function.