Re: polymorphic method override

From:
"Alf P. Steinbach" <alfps@start.no>
Newsgroups:
comp.lang.c++
Date:
Sat, 15 May 2010 23:49:08 +0200
Message-ID:
<hsn509$uov$1@news.eternal-september.org>
On 15.05.2010 23:36, * stf:

Why does this code not compile?

#include<iostream>

using namespace std;

class A {
    public:
        virtual void myMethod(const string& s) const;
};

class B : public A {
    public:
        virtual void myMethod(int x) const;
};

void A::myMethod(const string& s) const {
    cerr<< "(A) myMethod: s is: "<< s<< endl;
}
void B::myMethod(int x) const {
    cerr<< "(B) myMethod: x = "<< x<< endl;
}

int main() {
    std::string s("my string one");
    B b;
    b.myMethod(s);
    return 0;
}

The error is:

$ g++ -Wall ./test-5.cpp -o test-5.out ./test-5.cpp: In function
???int main()???:
./test-5.cpp:25: error: no matching function for call to
???B::myMethod(std::string&)???
./test-5.cpp:18: note: candidates are: virtual void B::myMethod(int)
const


This is a FAQ.

It's often a good idea to check the FAQ (or a textbook) before posting.

See http://www.parashift.com/c++-faq-lite/strange-inheritance.html#faq-23.9

Cheers & hth.,

- Alf

--
blog at <url: http://alfps.wordpress.com>

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