Expressions in Programming

Using Expressions

• What is a Variable?
• A variable is a named storage location in programming that can hold a value.

Characteristics of an Expression

• An expression is a combination of operators, literals (constants), and variables that computes a value.
• Operands: These are the values or variables that the operator acts upon.
• Operator: A symbol that performs a specific operation (e.g., *, /, +, etc.).

Types of Operators

1. Arithmetic Operators

• Used for mathematical calculations.
• Common arithmetic operators:
  • +: Addition
  • -: Subtraction
  • *: Multiplication
  • /: Division
  • ^: Exponentiation
  • %: Modulus (returns the remainder)
  • //: Integer division (returns an integer quotient.)
  • Examples:
  • sngPrice * 0.25 (where sngPrice is a variable representing a number)

1. Assignment Operators

• Used to assign values to variables.
• Types include:
  • =: Assign value (e.g., x = 6)
  • +=: Add and assign (e.g., x += 6 which is equivalent to x = x + 6)
  • -=: Subtract and assign (e.g., x -= 6)
  • *=: Multiply and assign (e.g., x *= 6)
  • /=: Divide and assign (e.g., x /= 6)
  • More specialized operators like ^= for exponentiation and &= for string concatenation.

1. Relational Operators

• Compare two values and return a boolean result (true or false).
• Types include:
  • <: Less than (e.g., a < b)
  • <=: Less than or equal to (e.g., a <= b)
  • >: Greater than (e.g., a > b)
  • >=: Greater than or equal to (e.g., a >= b)
  • =: Equal to (e.g., a = b)
  • <>: Not equal to (e.g., a <> b)

1. Logical Operators

• Used to combine multiple relational expressions.
• Types include:
  • AND: Returns true if both conditions are true.
  • OR: Returns true if at least one condition is true.
  • NOT: Reverses the truth value.

Order of Precedence

• Refers to the rules determining the order in which operations should be performed in an expression:

1. Parentheses ()
2. Exponentiation ^
3. Multiplication * and Division /
4. Addition + and Subtraction -

Practice Programs

• Program for Arithmetic Operations:
• Create a program that performs exponentiation, modulus division, and integer division on two inputted numbers.
• Relational and Logical Operators Program:
• Evaluate and illustrate the functions of comparison and logical operators using user input.
• Calculate Area, Perimeter, and Volume:
• Create a program that computes the area, perimeter, and volume of a square based on the input of the side length.

Test Your Knowledge

• Complete activities on pages 147 – 148 to reinforce knowledge.
• Engage in hands-on activities to practice concepts learned.