User Defined Conversions

Deleting Typecast Operators

Why might we want to delete a specific typecast operator?

Abstract art representing computer programming

Deleting a specific typecast operator can prevent unintended and potentially dangerous conversions. In C++, the delete keyword can be used to delete a function or operator, ensuring it cannot be used, even explicitly.

This is particularly useful for typecast operators that could lead to logic errors or bugs if used improperly.

Consider a scenario where we have a Vector class that can be converted to a bool but should not be converted to an int:

#include <iostream>

class Vector {
  float x, y, z;

  Vector(float x, float y, float z)
    : x(x), y(y), z(z) {}

  // Allow conversion to bool
  operator bool() {
    return x != 0 || y != 0 || z != 0;

  // Delete conversion to int
  operator int() = delete;  

int main() {
  Vector v(1.0f, 2.0f, 3.0f);

  if (v) {
    std::cout << "Vector is non-zero\n";

  // Error: conversion to int is deleted
  int value = v; 
error: attempting to reference a deleted function
note: 'Vector::operator int(void)': function was explicitly deleted

In this example, we define a Vector class with a typecast operator to bool to check if the vector is non-zero. However, we delete the typecast operator to int to prevent accidental or unintended conversions.

Deleting a typecast operator is useful in scenarios where:

  • The conversion does not make logical sense.
  • The conversion could lead to subtle bugs.
  • You want to restrict how the class can be used.

By explicitly deleting certain conversions, you make the code safer and more predictable. It forces the developer to think carefully about how objects are used and ensures that only meaningful conversions are allowed.

In summary, deleting typecast operators helps prevent misuse and maintains the integrity of your class by disallowing inappropriate or dangerous conversions.

Answers to questions are automatically generated and may not have been reviewed.

A computer programmer
Part of the course:

Professional C++

Comprehensive course covering advanced concepts, and how to use them on large-scale projects.

Free, unlimited access

This course includes:

  • 124 Lessons
  • 550+ Code Samples
  • 96% Positive Reviews
  • Regularly Updated
  • Help and FAQ
Free, Unlimited Access

Professional C++

Comprehensive course covering advanced concepts, and how to use them on large-scale projects.

Screenshot from Warhammer: Total War
Screenshot from Tomb Raider
Screenshot from Jedi: Fallen Order
Contact|Privacy Policy|Terms of Use
Copyright © 2024 - All Rights Reserved