Added functions for chapter 4

src/VariableBindings.rs

@@ -0,0 +1,24 @@
+pub mod Mutability;
+pub mod ScopeAndShadowing;
+pub mod DeclareFirst;
+pub mod Freezing;
+
+
+pub fn main(){
+	let an_integer = 1u32;
+	let a_boolean = true;
+	let unit = ();
+
+	//copy `an_integer` into `copied_integer`
+	let copied_integer = an_integer;
+
+	println!("An integer: {:?}", copied_integer);
+	println!("A boolean: {:?}", a_boolean);
+	println!("Meet the unit value: {:?}", unit);
+
+	//The compiler warns about unused variable bindings; these warnings can be silenced by prefixing the variable name with an underscore
+	let _unused_variable = 3u32;
+
+	//let noisy_unused_variable = 2u32;
+	//FIXME ^ Prefix with an underscore to suppress the warning
+}

src/VariableBindings/DeclareFirst.rs

@@ -0,0 +1,23 @@
+pub fn main(){
+	// Declare a variable binding
+	let a_binding;
+
+	{
+		let x = 2;
+
+		// Initialize the binding
+		a_binding = x * x;
+	}
+
+	println!("a binding: {}", a_binding);
+
+	let another_binding;
+
+	// Error! Use of uninitialized binding
+	//println!("another binding: {}", another_binding);
+	// FIXME ^ Comment out this line
+
+	another_binding = 1;
+
+	println!("another binding: {}", another_binding);
+}

src/VariableBindings/Freezing.rs

@@ -0,0 +1,17 @@
+pub fn main(){
+	let mut _mutable_integer = 7i32;
+
+	{
+		// Shadowing by immutable `_mutable_integer`
+		let _mutable_integer = _mutable_integer;
+
+		// Error! `_mutable_integer` is frozen in this scope
+		//_mutable_integer = 50;
+		// FIXME ^ Comment out this line
+
+		// `_mutable_integer` goes out of scope
+	}
+
+	// Ok! `_mutable_integer` is not frozen in this scope
+	_mutable_integer = 3;
+}

src/VariableBindings/Mutability.rs

@@ -0,0 +1,15 @@
+pub fn main(){
+	let _immutable_binding = 1;
+	let mut mutable_binding = 1;
+
+	println!("Before mutation: {}", mutable_binding);
+
+	//Ok
+	mutable_binding += 1;
+
+	println!("After mutation: {}", mutable_binding);
+
+	//Error!
+	//_immutable_binding += 1;
+	//FIXME ^ Comment out this line
+}

src/VariableBindings/ScopeAndShadowing.rs

@@ -0,0 +1,29 @@
+pub fn main(){
+	// This binding lives in the main function
+	let long_lived_binding = 1;
+
+	// This is a block, and has a smaller scope than the main function
+	{
+		// This binding only exists in this block
+		let short_lived_binding = 2;
+
+		println!("inner short: {}", short_lived_binding);
+
+		// This binding *shadows* the outer one
+		let long_lived_binding = 5_f32;
+
+		println!("inner long: {}", long_lived_binding);
+	}
+	// End of the block
+
+	// Error! `short_lived_binding` doesn't exist in this scope
+	//println!("outer short: {}", short_lived_binding);
+	// FIXME ^ Comment out this line
+
+	println!("outer long: {}", long_lived_binding);
+	
+	// This binding also *shadows* the previous binding
+	let long_lived_binding = 'a';
+	
+	println!("outer long: {}", long_lived_binding);
+}

src/main.rs

@@ -4,6 +4,7 @@
 mod HelloWorld;
 mod Primitives;
 mod CustomTypes;
+mod VariableBindings;
 
 
 fn main(){
@@ -42,4 +43,15 @@ fn main(){
 	//CustomTypes::Enums::TestCaseLinkedList::main();
 	//3.3 Constants
 	//CustomTypes::Constants::main();
+
+	//4 Variable Bindings
+	VariableBindings::main();
+	//4.1 Mutability
+	VariableBindings::Mutability::main();
+	//4.2 Scope and Shadowing
+	VariableBindings::ScopeAndShadowing::main();
+	//4.3 Declare First
+	VariableBindings::DeclareFirst::main();
+	//4.4 Freezing
+	VariableBindings::Freezing::main();
 }