先把各家的解释复制在这里,意思都差不多。
You can tell the compiler to use the global identifier rather than the local identifier by prefixing the identifier with ::, the scope resolution operator.
Remarks
The identifier can be a variable or a function.
If you have nested local scopes, the scope resolution operator does not provide access to identifiers in the next outermost scope. It provides access to only the global identifiers.
Example
This example has two variables named amount. The first is global and contains the value 123. The second is local to the main function. The scope resol