Why does a string literal trigger the `bool` overload in function overloading?

String Literal Ambiguity in Function Overloading with bool

When defining overloaded methods that accept both bool and std::string arguments, developers may encounter unexpected behavior when providing string literals. Instead of invoking the std::string overload, the bool overload is prioritized.

To understand this behavior, consider the following situation:

<code class="cpp">class Output
{
public:
    static void Print(bool value)
    {
        std::cout << value ? "True" : "False";
    }

    static void Print(std::string value)
    {
        std::cout << value;
    }
};

Output::Print("Hello World");</code>

Despite providing a string literal, the Print() method with the bool overload is invoked. This is because string literals in C can be implicitly converted to bool values. Specifically, "Hello World" is a const char* array that can be interpreted as a pointer to a const char, which in turn can be implicitly converted to a bool. This conversion is considered a standard conversion sequence.

C prioritizes standard conversion sequences over user-defined conversions (e.g., the conversion from std::string to bool). According to the C standard (§13.3.3.2/2), a standard conversion sequence is always considered a better conversion sequence.

This behavior can be altered by explicitly providing an std::string argument to the Print() method:

<code class="cpp">Output::Print(std::string("Hello World"));</code>

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