Lecture Notes on Operator Precedence and Arithmetic Expressions

Operator Precedence Overview

• Parentheses have the highest precedence.
• Unary minus follows.
• Operators with the same priority:
  • Multiplication, Division, Modulus
  • Addition, Subtraction
• Evaluation of same priority operators is from left to right.
• Parentheses can change the precedence of evaluation.

Examples of Operator Precedence

Example Expression: A + B * C - D / E*

• To avoid confusion, parentheses can be used:
  • Equivalent to A + (B * C) - (D / E).
• Steps of evaluation:
  1. Calculate B * C (multiplication)
  2. Calculate D / E (division)
  3. Evaluate A + (result of B*C)
  4. Evaluate the final result*

Unary Operators

• Unary operators will automatically imply parentheses during computation.
• Example: If using -B, it means (-B).

Further Example: A - B + C + D

• Same priority operators evaluated left to right.
• Parentheses can determine specific order of operations:
  • E.g., ((A - B) + C) + D

Types of Arithmetic Expressions

Integer Arithmetic

• Operands are integers.
• Always yields integer values.

Real Arithmetic

• Involves floating point values.
• Example: 1.0 / 3.0 * 3.0 yields a real number.
• Rounding may occur due to significant digits.
• Modulus is not defined for real operands.*

Mixed Mode Arithmetic

• Combines integers and real numbers.
• Result is a real number if any operand is real.
• Example: 25 / 10 results in 2 (integer), while 25.0 / 10 results in 2.5 (real).

Assignment Operations

• Assign value from an expression or variable to another variable:
  • Example: V = U + F * T
• Ensure compatibility of data types (int vs float).
• Type casting may be necessary.*

Example of Type Casting

• Casting integer to fit into a floating point representation.
• Example: X = (int)(2 * R) where R is a float.*

Relational Operators

• Used for comparison between two quantities:
  • Less than (<)
  • Greater than (>)
  • Less than or equal to (<=)
  • Greater than or equal to (>=)
  • Equality (==) - checks value equality
  • Not equal to (!=)

Important Notes on Relational Operators

• They return only boolean values (0 or 1 for false or true).
• Example comparisons:
  • X < Y returns true if X is less than Y.

Use in Conditional Statements

• Example: Implementing logic:
  • If X > Y: Print "X is larger"
  • Else: Print "Y is larger"

Summary

• Covered operator precedence and its significance in expressions.
• Discussed integer arithmetic, real arithmetic, and mixed mode arithmetic.
• Introduced relational operators and their use in comparisons and decision-making.
• Next topic: Logical operators.