[RESOLVED] unfamiliar function declaration

[jcfuller]

I am experimenting with the c++11 regex and came across an item missing from my limited c++ knowledge.

From this article:
http://msdn.microsoft.com/en-us/magazine/dn519920.aspx

I am unfamiliar with this function with the -> operator?

auto begin(strip const & s) -> char const *
{
  return s.first;
}

Is this code the same?

char const* begin (strip const&  s)
{
    return s.first;
}

James

[2kaud]

Yes. This form of specifying the return type now tends to be used with templates.

[Alex F]

Yes, these two declarations are the same, and in this context there is no need to use the first one (though the code is correct). auto return type with -> return-type syntax is used in templates. You can read explanation here: http://stackoverflow.com/questions/2...nction-heading
This is short summary. Consider template function with T1 and T2 parameters, which returns the value of type t1 + t2 (t1 is variable of T1 type, and t2 is variable of T2 type). t1+t2 type is unknown before template instantiation. There are two ways to write such template:

template <typename T1, typename T2>
decltype(std::declval<T1>() + std::declval<T2>())
Add(T1 a, T2 b) 
{ 
     return a + b; 
}

template <typename T1, typename T2>
auto Add(T1 a, T2 b) -> decltype(a + b)
{
     return a + b; 
}

The second version is more readable.

[jcfuller]

Thank you gentlemen.
My education continues.

James