Class method and variable with same name, compile error in C++ not in Java?

Question

class Test {

      bool isVal() const {
          return isVal;
      }

  private:

      bool isVal;
};

On Compiling this file it says

testClass.cpp:9: declaration of `bool Test::isVal'

testClass.cpp:3: conflicts with previous declaration `bool Test::isVal()'

Although the same would work for java

class Test {

  private boolean isVal;

  public boolean isVal() {
      return isVal;
  }

}

Not sure why C++ cannot handle this.

Answer 1

Because C++ is not Java. You can take the address of a member:

&Test::isVal

So you can't have two members have the same name, except that you can overload member functions. Even if you could disambiguate that by some kind of cast, the next problem would already be served at another place. In C++, we usually call member variables specially, like putting a m before their name:

class Test {
public:
    bool IsVal() const { return mIsVal; }
private:
    bool mIsVal;
};

Answer 2

Functions in c/c++ are just pointers to a location in memory where the code is located, isVal (as a boolean) and isVal (as a function) are therefore ambiguous.

Answer 3

The quick answer is "because that's the way C++ works." C++ doesn't have a separate name space for member variables and member functions (ie, "methods") where Java (apparently, as I haven't tried this) does.

In any case, remember the old story about the guy who went to a doctor and said "Doc, it hurts when I do this." To which the doctor replied "well, don't do that!" This is a language peculiarity on its way to becoming a Dumb Programmer Trick.