Examples of Control Flow Statements in Rust

Introduction to Control Flow Statements in Rust

Control flow statements in Rust allow programmers to manage the execution flow of their code based on certain conditions. These statements include if, else, loop, while, for, and match, enabling developers to create dynamic and responsive applications. Below are three diverse examples that illustrate how control flow statements can be effectively utilized in Rust programming.

Example 1: Conditional Execution with If-Else

Context

In situations where a program needs to make decisions based on certain conditions, the if-else statement is a fundamental control flow construct. This example demonstrates how to check a user’s age and determine whether they are eligible to vote.

fn main() {
    let age = 20;
    if age >= 18 {
        println!("You are eligible to vote.");
    } else {
        println!("You are not eligible to vote.");
    }
}

Notes

• The if statement evaluates the condition (age >= 18) and executes the corresponding block of code based on the result.
• You can chain multiple conditions using else if for extended decision-making processes.

Example 2: Looping Through a Collection with For

Context

When you need to iterate through a collection, such as an array or a vector, the for loop is an efficient choice. This example shows how to use a for loop to iterate through a list of numbers and print each one.

fn main() {
    let numbers = vec![1, 2, 3, 4, 5];
    for number in &numbers {
        println!("Number: {}", number);
    }
}

Notes

• The &numbers syntax borrows the vector, allowing you to iterate without taking ownership.
• Using for loops is generally more idiomatic in Rust compared to traditional for loops found in other programming languages.

Example 3: Pattern Matching with Match

Context

The match statement provides a powerful way to compare a value against multiple patterns and execute code based on the matching pattern. This example illustrates how to use match to handle different types of user input.

fn main() {
    let input = "yes";
    match input {
        "yes" => println!("You agreed!"),
        "no" => println!("You disagreed!"),
        _ => println!("Invalid input!"),
    }
}

Notes

• The _ pattern acts as a catch-all for any input that doesn’t match the previous patterns, ensuring that your program can handle unexpected values gracefully.
• match statements can also be used with enums, making them extremely versatile for control flow in Rust applications.