Re: String and Char in function template

[Eljay Love-Jensen <eljay@xxxxxxxxx>]

Hi,

You've run into a few problems.

1) you are using the variables names "two" and "three" multiple times.  No 
good.

2) the std::greater is colliding with your greater.  Put your greater in 
your own namespace.  (This may be a GCC bug in the STL implementation.  Or 
maybe std::greater is supposed to be in the global namespace, I'm not sure.)

3) the char const* versions of two and three won't compare as you'd expect, 
it's doing a pointer comparison.  You need a template specialization to 
change the char const* situation.

HTH,
--Eljay

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#include <iostream>
#include <string>
using std::cout;
using std::string;

namespace learn_cpp
{

template <typename T> // template parameter list
T const& greater(T const& first, T const& second)
{
    return (first > second) ? first : second;
}

}

int main()
{
    int a = 1, b = 2;
    cout << learn_cpp::greater(a, b) << '\n';

    long c = 4L, d = 3L;
    cout << learn_cpp::greater(c, d) << '\n';

    double e = 5.62, f = 3.48;
    cout << learn_cpp::greater(e, f) << '\n';

    char g = 'A', h = 'a';
    cout << learn_cpp::greater(g, h) << '\n';

    string two1("two"), three1("three");
    cout << learn_cpp::greater(two1, three1) << '\n';

    char const* two2("two"), *three2("three");
    cout << learn_cpp::greater(two2, three2) << '\n';

    char const* two3("two"), *three3("three");
    cout << learn_cpp::greater(two3, three3) << '\n';

    return 0;
}