Question

HI,
I started learning C++ STL’s
i am just trying some small programs.one of them is below:

inline int const& max (int const& a, int const& b) 
{
    return  a < b ? b : a;
}

template <typename T>
inline T const& max (T const& a, T const& b)
{
    return  a < b ? b : a;
}

int main()
{
    ::max(7, 42);         // calls the nontemplate for two ints
    ::max<>(7, 42);       // calls max<int> (by argument deduction)
    ::max('a', 42.7);     // calls the nontemplate for two ints
}

I have some basic questions!!

1. why is the scope resolution
   operator used here?

2. why/how is
   that calling ::max<>(7, 42) will
   assume that the parameter passed are

   integers?

Answer 1

1) why is the scope resolution
operator used here?

Probably to differentiate the max declared here from the one in (for example) the std:: namespace.

2) why/how is that calling ::max<>(7, 42) will assume that the
parameter passed are integers?

It doesn’t have to assume anything – integer literals have the type int.

And to answer the question you didn’t ask:

 max('a', 42.7);

matches the non-template version because type conversions are not performed on templated parameters, but are performed on non-template ones.