c++ - Function template specialization importance and necessity

Question

I read C++ Primer, and it says function template specialization is an advanced topic, but I am totally lost. Can anybody offer an example why function template specialization is important and necessary?

Why don't function templates support partial specialization while class templates do? What's the underlying logic?

Answer 1

Your question of why functions do not support partial specialization can be answered here. The code below shows how to implement the different specializations.

template<typename T>
bool Less(T a, T b)
{
    cout << "version 1 ";
    return a < b;
}
// Function templates can't be partially specialized they can overload instead.
template<typename T>
bool Less(T* a, T* b)
{
    cout << "version 2 ";
    return *a < *b;
}

template<>
bool Less<>(const char* lhs, const char* rhs)
{
    cout << "version 3 ";
    return strcmp(lhs, rhs) < 0;
}

int a = 5, b = 6;

cout << Less<int>(a, b) << endl;
cout << Less<int>(&a, &b) << endl;
cout << Less("abc", "def") << endl;