Can we access global variable if there is a local variable with same name?

　　In C, we cannot access a global variable if we have a local variable with same name, but it is possible in C++ using scope resolution operator (::).

 1 #include<iostream>
 2 using namespace std;
 3
 4 int x;  // Global x
 5
 6 int main()
 7 {
 8     int x = 10; // Local x
 9     cout<<"Value of global x is "<<::x<<endl;
10     cout<<"Value of local x is "<<x;
11     getchar();
12     return 0;
13 }

　　

　　the C language doesn't have concept of 'resolving scope'. Even C++ can't resolve anonymous scope variables. In C++, since the basic abstraction and encapsulation mechanism (class) can also introduce scope and class variables are possible, a special operator for resolving scope is required. Also, in C++, we can't access function scope variables, nor file scope variables in another file.

　　For example, see

1 void scope_resolution(void)
2 {
3     static unsigned int i = 2;
4     {
5         static unsigned int i = 1;
6         cout << ::i << endl; // i is looked at global scope
7     }
8 }

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　　2013-11-27　　12:17:49