C++ Overloading

Overloading allows for more than one definition of a function or operator in the same scope. Respectively, it is called function overloading and operator overloading.

Function Overloading

Function overloading begins with declaring a function with the same name as a previously declared function but with different parameters.

Note: Each declaration must have different parameters. Only changing the function’s return type will not work.

Syntax

Since a function can be overloaded multiple times, the syntax can look different case-to-case. The following is an outline of what an overloaded function could look like:

functionName(parameters1);
functionName(parameters2);

More declarations can be added as needed and a declaration has the following parts:

• functionName: The name of the function that is the same for each definition.
• parameters1 and parameters2: Parameters for each definition, these must be different for each definition.

Example

The following example overloads the multiply() function:

#include <iostream>
using namespace std;

void multiply(int x, int y) {
  cout << "The product of " << x << " and " << y << " is: " << (x*y) << endl;
}

void multiply(double x, double y) {
  cout << "The product of " << x << " and " << y << " is: " << (x*y) << endl;
}

int main() {
  multiply(20,10);
  multiply(80.2, 90.99);
}

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This will output:

The product of 20 and 10 is: 200
The product of 80.2 and 90.99 is: 7297.4

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Operator Overloading

Operator overloading redefines built-in operators for user-defined classes. When an overloaded operator is called, the compiler determines which definition to use based on the arguments provided. The following operators can be overloaded:

The operators below cannot be overloaded:

Syntax

class className {
  public:
    returnType operator symbol (arguments) {
      // code goes here
    }
};

The operator keyword is used along with the following:

• className: Name of the class.
• returnType: Return type of the function.
• symbol: Operator in which to overload.
• arguments: Arguments to pass in.

Codebyte Example

The following codebyte example overloads the plus (+) operator within the Pyramid class and returns the volume of two pyramids added together:

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