**Course Title:** Kotlin Programming: From Basics to Advanced Techniques **Section Title:** Introduction to Kotlin and Setup **Topic:** Basic syntax: Variables, data types, and operators **Introduction** In this topic, we'll delve into the fundamental syntax of Kotlin programming language. We'll cover variables, data types, and operators, which form the backbone of any programming language. Mastering these concepts is crucial to writing efficient, readable, and maintainable Kotlin code. **Variables in Kotlin** In Kotlin, a variable is a storage location that holds a value. Variables have a name, a data type, and a value. There are two types of variables in Kotlin: mutable and immutable. * **Immutable Variables (val):** An immutable variable's value cannot be changed once it's assigned. To declare an immutable variable, use the `val` keyword. ```kotlin val name: String = "John Doe" // name = "Jane Doe" // This will result in a compilation error ``` * **Mutable Variables (var):** A mutable variable's value can be changed after it's assigned. To declare a mutable variable, use the `var` keyword. ```kotlin var age: Int = 30 age = 31 // This is allowed ``` **Data Types in Kotlin** Kotlin has a range of built-in data types, including numbers, characters, booleans, arrays, and strings. Here's a brief overview of each: * **Numbers:** Kotlin supports several numeric data types: * `Byte`: 8-bit signed integer * `Short`: 16-bit signed integer * `Int`: 32-bit signed integer * `Long`: 64-bit signed integer * `Float`: 32-bit floating-point number * `Double`: 64-bit floating-point number * **Characters:** Kotlin's `Char` data type represents a single character. It's declared using the `char` keyword. ```kotlin val letter: Char = 'A' ``` * **Booleans:** Kotlin's `Boolean` data type represents a boolean value, which can be either `true` or `false`. ```kotlin val isAdmin: Boolean = true ``` * **Arrays:** In Kotlin, arrays are used to store a collection of values of the same data type. They're declared using the `arrayOf()` function. ```kotlin val numbers: Array<Int> = arrayOf(1, 2, 3, 4, 5) ``` * **Strings:** Kotlin's `String` data type represents a sequence of characters. Strings are enclosed in double quotes. ```kotlin val greeting: String = "Hello, World!" ``` **Operators in Kotlin** Kotlin supports various operators, including arithmetic, comparison, logical, and assignment operators. * **Arithmetic Operators:** * `+`: Addition * `-`: Subtraction * `*`: Multiplication * `/`: Division * `%`: Modulus ```kotlin val sum: Int = 5 + 3 // sum = 8 val difference: Int = 5 - 3 // difference = 2 ``` * **Comparison Operators:** * `==`: Equal to * `!=`: Not equal to * `>`: Greater than * `<`: Less than * `>=` : Greater than or equal to * `<=`: Less than or equal to ```kotlin val isEqual: Boolean = 5 == 5 // isEqual = true val isNotEqual: Boolean = 5 != 3 // isNotEqual = true ``` * **Logical Operators:** * `&&`: Logical AND * `||`: Logical OR * `!`: Logical NOT ```kotlin val isAdminAndActive: Boolean = true && true // isAdminAndActive = true val isAdminOrActive: Boolean = true || false // isAdminOrActive = true val isNotAdmin: Boolean = !true // isNotAdmin = false ``` * **Assignment Operators:** * `=`: Assign * `+=`: Add and assign * `-=`: Subtract and assign * `*=`: Multiply and assign * `/=`: Divide and assign * `%=`: Modulus and assign ```kotlin var number: Int = 5 number += 3 // number = 8 ``` **Conclusion** In this topic, we've explored the basic syntax of Kotlin programming language, including variables, data types, and operators. We've learned about the different types of variables, data types, and operators Kotlin supports. Understanding these concepts is essential to writing efficient, readable, and maintainable Kotlin code. **Practice Time** Try practicing what you've learned by attempting the following exercises: 1. Declare a mutable variable and assign it a value. Then, reassign the variable a new value. 2. Declare an immutable variable and try reassigning it a new value. What error message do you receive? 3. Create a string variable and use string concatenation to combine two strings. 4. Use the comparison operator to check if two variables are equal. What is the result? **What's Next?** In the next topic, we'll cover writing your first Kotlin program: "Hello, World!". We'll explore the basics of program structure, functions, and printing output to the console. **Need Help?** If you're having trouble understanding any of the concepts covered in this topic or need help with your exercises, feel free to leave a comment. **Reference Links** * [Kotlin Documentation: Variables](https://kotlinlang.org/docs/reference/variables.html) * [Kotlin Documentation: Data Types](https://kotlinlang.org/docs/reference/basic-types.html) * [Kotlin Documentation: Operators](https://kotlinlang.org/docs/reference/expressions.html)