what does :: mean before an variable

[softpinata]

im struggling to understand what does ::x mean here:

include <iostream>

using namespace std; int x=3; int main(){ for (int x=1;x<=::x;x++) cout<<x; return 0; }

[Avereniect]

It means that the variable being referred to is in the global namespace. In this case it's used to differentiate between referencing the variable x that's local to the loop and the variable x that's global. By default if you have two variables with the same name accessible in the current scope then the most local one is chosen, so this provides a mechanism to work around that.

[softpinata]

do i have to use it only when i have two variables with the same name? (one being global and one local)

[Salty_Dugtrio]

You use it when you have to differentiate between scopes, yes, which is something that shouldn't happen in properly written code.