Swift Basic Syntax

Swift Syntax Rules

let name = "John"
print(name) // No semicolon needed

let Name = "John"
let name = "Jane" // Different variables

// Single line comment
/* Multi-line
   comment */

let userName = "Alice"
func calculateAge() { }

🔹 Variables and Constants

Swift uses var for variables and let for constants:

// Variables (can change)
var age = 25
var name = "John"
age = 26  // This is allowed

// Constants (cannot change)
let birthYear = 1998
let country = "USA"
// birthYear = 1999  // This would cause an error

print("Name: \(name)")
print("Age: \(age)")
print("Born in: \(birthYear)")
print("Country: \(country)")

🔹 Data Types

Swift has several built-in data types:

// String
let message: String = "Hello, World!"

// Integer
let count: Int = 42

// Double (decimal numbers)
let price: Double = 19.99

// Boolean
let isActive: Bool = true

// Character
let grade: Character = "A"

// Type inference (Swift guesses the type)
let autoString = "This is a string"  // Swift knows it's String
let autoNumber = 100                 // Swift knows it's Int

print("Message: \(message)")
print("Count: \(count)")
print("Price: $\(price)")
print("Active: \(isActive)")
print("Grade: \(grade)")

🔹 String Interpolation

Embed variables and expressions inside strings:

let firstName = "John"
let lastName = "Doe"
let age = 30

// String interpolation with \()
let introduction = "Hi, I'm \(firstName) \(lastName) and I'm \(age) years old."
print(introduction)

// You can use expressions too
let nextYear = "Next year I'll be \(age + 1) years old."
print(nextYear)

// Mathematical expressions
let width = 10
let height = 5
let area = "The area is \(width * height) square units."
print(area)

🔹 Basic Operators

Swift supports common mathematical and logical operators:

// Arithmetic operators
let a = 10
let b = 3

print("Addition: \(a + b)")        // 13
print("Subtraction: \(a - b)")     // 7
print("Multiplication: \(a * b)")  // 30
print("Division: \(a / b)")        // 3
print("Remainder: \(a % b)")       // 1

// Comparison operators
print("Equal: \(a == b)")          // false
print("Not equal: \(a != b)")      // true
print("Greater than: \(a > b)")    // true
print("Less than: \(a < b)")       // false

// Logical operators
let isTrue = true
let isFalse = false

print("AND: \(isTrue && isFalse)") // false
print("OR: \(isTrue || isFalse)")  // true
print("NOT: \(!isTrue)")           // false

🔹 Print Function

The print() function displays output:

// Basic print
print("Hello, World!")

// Print multiple items
print("Name:", "John", "Age:", 25)

// Print with separator
print("Apple", "Banana", "Orange", separator: " - ")

// Print without newline
print("Loading", terminator: "")
print("...", terminator: "")
print("Done!")

// Print with custom separator and terminator
print("Item 1", "Item 2", "Item 3", separator: " | ", terminator: " END\n")