Template allows to implement a generic functions that works with certain types. During compile time, type specific versions (image) of the function is generated.

Generic function code

template<typename T>
T mymax(T a, T b) {
	return b < a ? a : b;
}

// calling mymax function
mymax(3, 4);
mymax<string>("abc", "def"); // can specify the type

• T is a placeholder of a type

Generic function with multiple template parameters

template<typename T1, typename T2>
auto mymax(const T1& a, const T2& b) {
	return b < a ? a : b;
}

• return type of the function is deduced during compile time
• compiler deduces a common type - superset
  • behind the scene std::common_type_t<T1, T2>