Function Templates vs Function Overloading

Function templates and function overloading are two different mechanisms in C++ that allow you to define multiple versions of a function, but they serve different purposes.

1. Function Overloading:
   • Function overloading refers to defining multiple functions with the same name but different parameter types or numbers.
   • The compiler selects the appropriate function to call based on the arguments passed during the function invocation.
   • Function overloading is resolved at compile-time based on the static types of the arguments.
   • Each overloaded function has its own specific implementation.
2. Function Templates:
   • Function templates define a generic function that can work with different types.
   • The template parameters are placeholders for types that are determined when the function is instantiated.
   • The compiler generates a specific function based on the template arguments used during the function invocation.
   • Function templates provide a way to write generic code that can be reused for different types.

When to use each:

• Use function overloading when you need to define different implementations for functions with the same name but different parameter types or numbers.
• Use function templates when you have a generic algorithm or operation that can be applied to different types, and you want to write reusable code.

Example:

1// Function overloading
2int add(int a, int b) {
3  return a + b;
4}
5
6double add(double a, double b) {
7  return a + b;
8}
9
10// Function template
11template <typename T>
12T multiply(T a, T b) {
13  return a * b;
14}
15
16int main() {
17  // Calls add(int, int)
18  int intSum = add(5, 10);
19  
20  // Calls add(double, double)
21  double doubleSum = add(3.14, 2.71);
22  
23  // Instantiates multiply<int>(int, int)
24  int intProduct = multiply(4, 6);
25  
26  // Instantiates multiply<double>(double, double)
27  double doubleProduct = multiply(1.5, 2.0);
28}

In this example, add is overloaded for int and double types, providing specific implementations for each. On the other hand, multiply is a function template that can be instantiated for different types, generating the appropriate function based on the template arguments.