Function Overloading and Templates

An overload set contains functions with the same name but different parameter lists. The compiler chooses the best viable function using conversion rankings. Return type alone cannot distinguish overloads, and excessive implicit conversions can create ambiguity.

void print(int value);
void print(double value);
void print(const char* value);

template <typename T>
T maximum(const T& left, const T& right) {
    return left < right ? right : left;
}

A function template is a recipe instantiated for concrete arguments. Class templates parameterize data structures and policies. Template definitions normally live in headers because the compiler must see them at the point of instantiation.

Concepts and specialization

#include <concepts>

template <std::totally_ordered T>
const T& smaller(const T& a, const T& b) {
    return b < a ? b : a;
}

Concepts express requirements and improve both APIs and diagnostics. Before C++20, SFINAE and type traits commonly constrained templates. Function templates can be explicitly specialized, but overloads are often clearer; class templates support partial specialization.

Perfect forwarding uses a forwarding reference T&& plus std::forward<T> to preserve the caller’s value category. Use it only in generic adapter code, because it enlarges overload sets and diagnostics. Prefer the smallest interface that satisfies real types, test templates with varied argument categories, and avoid assumptions not stated by constraints.