Pitfalls of C++’s subscript operator

September 23, 2004 at 12:59 am (PT) in Programming

What’s wrong with this C++ code?

#include <iostream>
#include <string>


class Foo
{
public:
    Foo()
    {
    }


    operator bool()
    {
        return true;
    }


    std::string operator[](const std::string& s)
    {
        return s;
    }
};


int main(void)
{
    Foo foo;
    std::cout << foo["hello world!"] << std::endl;
    return 0;
}

Answer:

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