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

x is defined at the left of =.

so in x[x], [x] refer to the global one,

whereas in x = x;, x hides the global x and initializes from itself -> UB.