C++ Multiple Variables

C++ lets several variables of the same type be declared, and optionally initialized, in a single comma-separated statement, and supports chained assignment across multiple variables.

In this page:

Declaring Multiple Variables of the Same Type
Declaring and Initializing Together
Multiple Variables of Different Types
Multiple Assignment in One Statement
Readability Considerations

Declaring Multiple Variables of the Same Type

Multiple variables of the same type can be declared in a single statement by separating their names with commas after one type keyword, avoiding the repetition of writing the type multiple times.

Example: Declaring Multiple Variables of the Same Type

cpp

#include <iostream>

int main() {
	int x, y, z;
	std::cout << "Declared x, y, z with one int keyword" << std::endl;
	return 0;
}

Declaring and Initializing Together

Each variable in a comma-separated declaration can also be given its own initial value, combining declaration and initialization for several variables of the same type in one line.

Example: Declaring and Initializing Together

cpp

#include <iostream>

int main() {
	int x = 1, y = 2, z = 3;
	std::cout << x << " " << y << " " << z << std::endl;
	return 0;
}

Multiple Variables of Different Types

A single declaration statement can only introduce variables of one specific type, so variables of different types, like an int and a float, must always be declared in separate statements.

Example: Multiple Variables of Different Types

cpp

#include <iostream>

int main() {
	int age = 25;
	float price = 9.99f; // different type needs its own statement
	std::cout << age << " " << price << std::endl;
	return 0;
}

Multiple Assignment in One Statement

C++ allows chained assignment, such as x = y = z = 10, which evaluates right to left, assigning the same value to multiple variables in a single expression statement.

Example: Multiple Assignment in One Statement

cpp

#include <iostream>

int main() {
	int x, y, z;
	x = y = z = 10; // evaluated right to left
	std::cout << x << " " << y << " " << z << std::endl;
	return 0;
}

Readability Considerations

While declaring many variables on one line saves space, grouping only closely related variables together and keeping unrelated ones on separate lines generally keeps code easier to read and maintain.

Example: Readability Considerations

cpp

#include <iostream>

int main() {
	int width, height; // closely related, grouped together
	int score = 0;      // unrelated, kept on its own line
	width = 10; height = 5;
	std::cout << width << " " << height << " " << score << std::endl;
	return 0;
}

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