Rust Operators and Checked Arithmetic

How it works

Arithmetic operators work on typed values, and integer division truncates according to the integer rules rather than producing a fraction. Overflow behaviour depends on the operation and configured checks. For user-supplied quantities, checked arithmetic returns Option so the caller must handle the out-of-range case. This is a numerical boundary decision, separate from ownership safety.

Run the code

Reviewed with Rust 1.97.0, edition 2024, using the standard library only. Save the complete download as lesson-name.rs in a separate learning folder, compile with rustc --edition=2024 lesson-name.rs and run the resulting program (lesson-name.exe on Windows). Use the actual lesson filename. The final project includes complete Cargo package files; run cargo test --offline and cargo run --offline from that separate package folder. There is no Rust browser runner; PHP, Apache and MySQL are not needed.

This complete example was executed in the stated local review environment.

Download complete source

Example

fn main() {
    assert_eq!(7_u32 / 3, 2);
    assert_eq!(255_u8.checked_add(1), None);
    assert_eq!(6_u32.checked_mul(3), Some(18));
    println!("Integer division is 2; overflow refused; product is 18");
}

Expected result

Integer division is 2; overflow refused; product is 18

The examples compare three distinct contracts: integer division, an overflowing addition and a valid multiplication. Use a larger type only if its range actually covers the domain; it does not remove the need to validate external quantities. A floating-point amount also has rounding and finite-value concerns.