main.cpp

/***************************************************************************
 *  @file       main.cpp
 *  @author     Alan.W
 *  @date       07  Feb 2014
 *  @remark     This code is for the exercises from C++ Primer 5th Edition
 *  @note
 ***************************************************************************/
//!
//! Exercise 16.37:
//! The library max function has two function parameters and returns the
//! larger of its arguments. This function has one template type parameter.
//! Could you call max passing it an int and a double? If so, how? If not,
//! why not?
//  If so, it doesn't compile, because the two argument must be the same type or
//  convertible.
//
//! Exercise 16.38:
//! When we call make_shared (§ 12.1.1, p. 451), we have to provide an
//! explicit template argument. Explain why that argument is needed and
//! how it is used.
//!
//  without specified type given, make_shared has no possibility to
//  to determine how big the size it should allocate, which is the reason.
//
//  Depending on the type specified, make_shared allocates proper size of memory
//  space and returns a proper type of shared_ptr pointing to it.
//!
//! Exercise 16.39:
//! Use an explicit template argument to make it sensible to pass two string
//! literals to the original version of compare from § 16.1.1 (p. 652).
//!


#include <iostream>


template <typename T>
int compare(const T &v1, const T &v2)
{
    if (v1 < v2) return -1;
    if (v2 < v1) return 1;
    return 0;
}

int main()
{
    std::cout << compare<std::string>("sss","aaa") << "\n";
                //!     ^^^^^^^^^^^^^
                //! There is a normal conversion here, since it's an explicit argument.



}