Variable and Constants

In Swift, variables and constants are used to store values of different types like Int, String, Bool, etc. Variables are mutable, meaning their values can change after they are initialized, while constants are immutable, meaning their values cannot change once set.

Concepts:

1. Variables (var):

   • Declaration: Declared using the var keyword followed by a name and optional type annotation (: Type).
   • Example:

     var age: Int = 30
     age = 31 // Valid: Changing the value of a variable

2. Constants (let):

   • Declaration: Declared using the let keyword followed by a name and optional type annotation (: Type).
   • Example:

     let name: String = "John"
     // name = "Jane" // Error: Cannot assign to value: 'name' is a 'let' constant

3. Type Inference:

   • Concept: Swift uses type inference to automatically determine the type of a variable or constant based on the initial value assigned.
   • Example:

     var temperature = 25.5 // Inferred as Double
     let message = "Welcome!" // Inferred as String

4. Mutability:

   • Variables (var): Mutable; their values can be changed after initialization.
   • Constants (let): Immutable; their values cannot be changed once set.

5. Naming Conventions:

   • CamelCase: Preferred naming convention for variables and constants (myVariable, myConstant).
   • Meaningful Names: Use descriptive names to indicate the purpose or content of the variable or constant.

Example:

// Example demonstrating variables and constants
var count: Int = 10
count = 15 // Valid: Changing the value of a variable

let pi: Double = 3.14
// pi = 3.14159 // Error: Cannot assign to value: 'pi' is a 'let' constant

// Type inference example
var message = "Hello, World!" // Inferred as String
var number = 42 // Inferred as Int

// Naming conventions
let firstName: String = "Alice"
var numberOfStudents: Int = 30

Concepts :

• Variables (var): count is declared as a variable and its value is mutable (Int).
• Constants (let): pi is declared as a constant and its value is immutable (Double).
• Type Inference: Swift infers the type of message and number based on their initial values.
• Naming Conventions: firstName and numberOfStudents follow Swift's naming conventions for variables and constants.