C++ Variables, Types & References

About C++

C++ is a compiled programming language that offers close control over memory and performance. It supports several programming styles and is often chosen for software that must use hardware efficiently.

• Game engines
• Native applications
• Systems software

Created by

Bjarne Stroustrup at Bell Labs

First released

1985 · first commercial release

Version / standard

C++23

Current published ISO standard (ISO/IEC 14882:2024). Compiler support varies.

In the real world

• Google: The Chromium browser project
• Epic Games: Unreal Engine development
• Adobe: Documented use in Photoshop

Facts checked 8 September 2026. Links open the sources; examples describe specific products or documented uses.

Syntax

int count = 3;
std::string name = "Ada";
int& alias = count;

Examples

#include <iostream>
int main() {
    int lessons = 3;
    int& alias = lessons;
    alias += 1;
    std::cout << lessons << "\n";
}

#include <iostream>

int main() {
  int count = 3;
  int& alias = count;
  alias += 1;
  std::cout << count << "\n";  // 4
}

Best practices

• Prefer const references for read-only parameters of larger objects to avoid unnecessary copies while making intent clear.
• Keep examples small while learning, then combine the idea with a real project.

At a glance

Purpose

Systems and general-purpose software

File extension

.cpp · .hpp

Runs in

Compiled native applications

Usually used with

Compiler and standard library

In plain English

A C++ variable has a type. A reference is an alias for an existing object, so assigning through it changes that object.

What you’ll learn

• Initialise a variable.
• Create a reference.
• Distinguish copying from aliasing.

Breaking down the syntax

int

An integer type.

& in a declaration

Declares an lvalue reference in this example.

const

Prevents modification through a const-qualified name or reference.

How it works

Object

Create a value with an initializer.

Reference

Bind an alias to that object.

Assignment

Modify the object through the alias.

When should I use this?

Use values for independent data and references when an operation should refer to an existing object.

Common mistakes

A common trap

An ordinary local reference declaration requires an initializer.

Incorrect

int& reference; // missing initializer

Corrected

int value = 3;
int& reference = value;

Compare approaches

• Value copy: A separate value that can change independently.
• Reference: An alias that must not outlive its referent.

Explore deeper

Lifetime matters

A reference does not own the object it names. Never return a reference to an ordinary local variable that is destroyed when the function returns.

Specifications & further reading

• Official language reference for this topic

Related C++ documentation