Using a variable with the same name in different spaces

Question

This code compiles, but I have a run time error in Visual Studio:

Run-time check failure #3 - the variable \'x\' is being used without being initializ

Answer 1

please use SRO( Scope resolution operator ::) to tell compiler which x is real x in your mind. As user defined names are mangled( Names are decorated) something like this to avoid ambiguity at it's level, these are just names used by compiler that best suits it

int x = 15;// Real name = gui_x
int main()
{
    int x = x;// lui_x
    return 0;
}

In this way run-time will know which version you are using but to avoid ambiguity it expects from you to use specific names. Sometimes above problem arise where you don't know that you are using already used names. For this C++ has created SRO.
Now in case of array x is address & not integer that stores something, that's why compiler didn't jumbled. You need to write

namespace abc //now all global variables are belongs to this ns abc
int x = 15;// Real name = gui_x
int main()
{
int x = abc::x;// lui_x
return 0;
}