Constants in Rust - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a constant in Rust?

A constant in Rust is a value that is bound to a name and cannot be changed. It must be set to a constant expression and is always immutable.

beginner

How do you declare a constant in Rust?

You declare a constant using the <code>const</code> keyword, followed by the name in uppercase, a type annotation, and a value. For example: <code>const MAX_POINTS: u32 = 100_000;</code>

beginner

Can constants in Rust be mutable?

No, constants in Rust are always immutable. You cannot change their value after declaration.

intermediate

Where are constants stored in Rust?

Constants are stored directly in the program's binary and embedded at compile time. They do not occupy memory at runtime like variables.

intermediate

What is the difference between a constant and a static variable in Rust?

Constants are always immutable and must be set to a compile-time value. Static variables have a fixed memory location and can be mutable with unsafe code. Constants do not have a fixed memory address.

How do you declare a constant named PI with a value of 3.14 in Rust?

A const PI: f64 = 3.14;

B let PI = 3.14;

C static PI = 3.14;

D var PI: f64 = 3.14;

Constants use the const keyword with a type annotation and value.

Can you change the value of a constant after it is declared in Rust?

A No, constants are immutable.

B Only inside functions.

C Yes, anytime.

D Only if declared mutable.

Constants are always immutable and cannot be changed.

What is the naming convention for constants in Rust?

A snake_case

B UPPERCASE_WITH_UNDERSCORES

C camelCase

D PascalCase

Constants are conventionally named in uppercase letters with underscores.

Which of these is true about constants in Rust?

A They can be assigned values at runtime.

B They are stored on the heap.

C They can be mutable.

D They must have a type annotation.

Constants must have explicit type annotations and are set at compile time.

What keyword is used to declare a constant in Rust?

A let

B var

C const

D static

The const keyword declares constants.

Explain how to declare and use constants in Rust, including naming conventions and immutability.

Think about how constants differ from variables.

Describe the difference between constants and static variables in Rust.

Consider mutability and memory storage.