Question

right now i am learning C++, and now I know the basic concept of template,
which act just like a generic type,
and i found almost every c++ program used template,
So i really want to know when are we supposed to use template ?
Can someone conclude your experience for me about c++ template ?
When will you consider to use template ?

Supplement:
if we defined such function

template <class myType>
myType GetMax (myType a, myType b) {
 return (a>b?a:b);
}

but we want to pass a object(self-defined class) for comparison, how can we implement ?

Supplement2:
in the answer below, someone have wrote this sample code

template <class myType>
const myType& GetMax (const myType& a, const myType& b) {
    return (a<b?b:a);
}

template <class myType, class Compare>
const myType& GetMax (const myType& a, const myType& b, Compare compare) {
    return (compare(a,b)?b:a);
}

is this correct ? can we just pass a function name as a parameter of class myType ?

Answer 1

Re: supplement. If you want to pass a comparison function, you could provide another overload:

template <class myType>
const myType& GetMax (const myType& a, const myType& b) {
    return (a<b?b:a);
}

template <class myType, class Compare>
const myType& GetMax (const myType& a, const myType& b, Compare compare) {
    return (compare(a,b)?b:a);
}

Samle usage: to compare C-style strings:

bool c_strings_less(const char* a, const char* b)
{
    return std::strcmp(a, b) < 0; //is a less than b
}

const char* greater = GetMax("hello", "world", c_strings_less);

This is how the std::max algorithm works. (I also made a few modifications, e.g it is customary in C++ that predicates define “less-than” comparison.)

Or if you asked, how GetMax would work for arbitrary user-defined types, then those must overload operator> or your function would result in a compile error.