Thread: Strange program behavior

Hey folks,

please have a look at this simple class:

Code:

#include <initializer_list>
#include <string>

class test {
public:
    test(std::string value, bool flag=false)
    {
    }
    
    test(std::initializer_list<std::string> values, bool flag=false)
    {
    }
};

Now, when testing this in I get quite strange results:

Code:

int main() // compiles fine
{
    test first{"abc"};
}

Code:

int main() // throws a `std::lenght_error' with `what():  basic_string::_S_create'
{    test second{{"abc", "def"}};
}

Code:

int main() // fine again
{
    test first{"abc"};
    test second{{"abc", "def"}};
}

I really don't understand how the construction of the instance `first' can resolve whatever problem the `second' instance encounters. Is there any logical explanation for this?

Thanks!

Ah clever trick, this works.. Thanks! I assumed that the `initializer_list' would require its own braces as soon as there are other parameters to choose from. I'll consider my problem to be solved, but I'd still be happy if someone could explain me how `first' can influence `second'.

Just a stab in the dark: maybe it has to do with how the compiler strongly prefers the initializer list overload? Maybe test first() also calls the initializer list constructor? Then because the latter scenario contains calls to both constructors, the compiler can make sense out of the double braces.

Thanks to you all for your efforts!