Summary of Chapter 3: Common Programming Concepts

Chapter 3 of the Rust Programming Language Book introduces several fundamental programming concepts that are essential for writing Rust programs. Below is a summary of the key points covered in this chapter.

Key Concepts

1. Variables and Mutability

Mutability: To make a variable mutable, you use the mut keyword.

let mut y = 5; // Mutable
y = 10; // Now this is allowed

Variables: By default, variables in Rust are immutable. This means once you assign a value to a variable, you cannot change it.

let x = 5; // Immutable

2. Data Types

• Rust has several built-in data types, including:
  • Scalar Types: Represent a single value (e.g., integers, floating-point numbers, booleans, characters).
  • Compound Types: Group multiple values into one (e.g., tuples, arrays).

Example of Scalar and Compound Types:

let a: i32 = 10; // Scalar
let b: f64 = 3.14; // Scalar
let tuple: (i32, f64) = (10, 3.14); // Tuple
let array: [i32; 3] = [1, 2, 3]; // Array

3. Functions

• Functions in Rust are defined using the fn keyword.
• They can take parameters and return values.

Example of a Function:

fn add(x: i32, y: i32) -> i32 {
    x + y // The return value is implicit
}

4. Control Flow

• Control flow statements determine the order in which code is executed.
• Conditional Statements: Use if, else if, and else to execute code based on conditions.

Example of Conditional Statement:

let number = 5;
if number < 5 {
    println!("Less than 5");
} else if number == 5 {
    println!("Equal to 5");
} else {
    println!("Greater than 5");
}

• Loops: Rust provides loop, while, and for for iteration.

Example of a Loop:

for i in 1..5 { // Range from 1 to 4
    println!("{}", i);
}

5. Comments

• Comments are crucial for code clarity and are ignored by the compiler.
• Use // for single-line comments and /* */ for multi-line comments.

Conclusion

Understanding these foundational concepts is crucial for anyone starting with Rust. Mastering variables, data types, functions, control flow, and comments will empower you to write efficient and organized Rust programs. As you progress in learning Rust, you will find these concepts recurring in various contexts.