IMAD

Understanding Variables in Programming

Definition of Val

• Val: A keyword used to declare a variable in programming.

  • Essential for defining variables; without it, you cannot declare a variable.

  • Syntax: val <variable_name>.

  • Example: val myNum.

Variable Names

• Each variable name must be unique; no two variables can share the same name within the same scope.

• Variable names can be any string that follows naming conventions.

  • Examples: myNum, num, number, nO.

Data Types

• Importance of data types in programming.

  • Common data types include:

    • Boolean: Represents true or false.

    • Integer: Represents whole numbers without decimals.

    • Double: Represents numbers with decimals and also accepts whole numbers as inputs.

Declaring Variables

• To declare a variable, use:

  • val <variable_name> : <data_type> = <value>.

  • Example: val myNum: Int = 1000.

  • Important Note: The value assigned to a val variable is static; it cannot be changed once set.

Static vs. Dynamic Variables

• Static: Once defined, the variable cannot change its value. For example, val myNum: Int = 1000.

• Dynamic variables can change; they are not declared with val.

Understanding Data Types: Int and Double

• Integer (Int):

  • Accepts only whole numbers.

  • Example: val myNum: Int = 100.

• Double:

  • Accepts decimal values as well as whole numbers.

  • Example: val myNum: Double = 100.0.

  • Note: Using a double for variables that will never have decimal values is considered bad practice, as it indicates confusion regarding data type requirements.

Proper Coding Practices

• Always choose a variable type based on the expected user input.

  • Example: For age, use an integer instead of a double, as age cannot be a decimal.

  • For lengths that can have decimal values, a double is appropriate.

Additional Data Types

• Char: Represents a single character (e.g., 'a').

  • Syntax: val myGrade: Char = 'A'.

• String: Can hold a sequence of characters including letters, spaces, and special symbols.

  • Syntax: val myName: String = "Bob".

Summary of Declaring Variables

• The order of declaration is always:

  1. val

  2. <variable_name>

  3. <data_type>

  4. = followed by the assigned value.

• Example of String declaration:

  • val myName: String = "Bob".

Key Takeaways

• Understand the function of val for variable declaration and the importance of using correct data types based on expected data.

• Following good coding practices prevents errors and improves the readability and maintainability of the code.