Functions in C++

Simple Example

#include <iostream>

std::string greet(std::string x){
    return "Hello, " + x + "!";
}

int main(){
    std::cout<<greet("Deep")<<"\n";
}

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Function overloading

• multiple functions can have the same name with different parameters.

int plusFuncInt(int x, int y) {
  return x + y;
}

double plusFuncDouble(double x, double y) {
  return x + y;
}

int main() {
  int myNum1 = plusFuncInt(8, 5);
  double myNum2 = plusFuncDouble(4.3, 6.26);
  cout << "Int: " << myNum1 << "\n";
  cout << "Double: " << myNum2;
  return 0;
}

Danger

• You can't overload a function with same name, same parameter numbers and type, but different return type.

Function overloading compile-time V/S Runtime performance

• Function Overloading requires the compiler to perform name mangling on the function name to include information about the argument types.

name mangling: modifying name (List_my.get -> List__my_get)

• Since, name mangling is done at compile-time, so compile time increases.
• But, during runtime, function (with mangled name) is called directly, so no performance penalty.

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Function Overloading V/S Overriding

• function overloading means having multiple functions with same name, but different parameter count or types.
• function/method overriding is when we override a base/default method present in base class in an inherited derived class.