Operators in C++

# CHAPTER 5

Operators in C++ #

1. Introduction #

2. Learning Objectives #

• Perform calculations using Arithmetic Operators.

• Compare values using Relational Operators.

• Combine conditions using Logical Operators.

• Use Assignment and Increment/Decrement operators.

• Understand basic Bitwise operators.

3. Arithmetic Operators #

Important Note on Division: If you divide two integers, C++ truncates the decimal. 5 / 2 results in 2. To get 2.5, at least one number must be a float: 5.0 / 2.

4. Increment and Decrement Operators #

Prefix vs. Postfix:

int a = 5;
int b = a++; // Postfix: assigns 'a' to 'b' THEN increments 'a'. (b=5, a=6)

int x = 5;
int y = ++x; // Prefix: increments 'x' THEN assigns to 'y'. (y=6, x=6)

5. Relational (Comparison) Operators #

6. Logical Operators #

7. Assignment Operators #

8. The Ternary Operator (?:) #

int age = 20;
// If age >= 18, assign true, else assign false.
bool is_adult = (age >= 18) ? true : false; 

9. Operator Precedence #

1. 1. () Parentheses

1. 2. ++, --, ! (Unary)

1. 3. *, /, % (Multiplication/Division/Modulus)

1. 4. +, - (Addition/Subtraction)

1. 5. <, >, <=, >= (Relational)

1. 6. ==, != (Equality)

1. 7. && (Logical AND)

1. 8. || (Logical OR)

1. 9. =, +=, -= (Assignment)

Best Practice: When in doubt, use parentheses () to force the order you want.

10. Memory-Level Explanation #

1. 1. The CPU fetches the value of a from RAM into a CPU register.

1. 2. The CPU fetches the value of b into another register.

1. 3. The Arithmetic Logic Unit (ALU) inside the CPU adds them.

1. 4. The result is pushed back into the RAM address of c.

11. Common Mistakes #

• Confusing = and ==: x = 5 assigns 5 to x. x == 5 checks if x is 5. Using = in an if statement is a massive source of logical bugs.

• Modulus on floats: The % operator ONLY works with integers.

• Integer Division: Forgetting that 5 / 2 yields 2, not 2.5.

12. Exercises #

1. 1. Write a program that calculates the area and perimeter of a rectangle.

1. 2. Demonstrate the difference between x++ and ++x using cout.

1. 3. Create a program that determines if a number is even or odd using the modulus operator (%).

13. MCQ Quiz with Answers #

14. Interview Questions #

• Q: Explain short-circuit evaluation in logical operators.

• Q: Without using a temporary variable, how can you swap two numbers? (Hint: arithmetic or XOR).

• Q: Why does C++ truncate integer division, and how do you prevent it?

15. Summary #

16. Next Chapter Recommendation #