Lecture 6: Logical Operators and Conditional Statements

1. Operators

Arithmetic Operators

Used to perform common mathematical operations.

Operator	Description	Example (N1=10, N2=5)	Result
+	Addition	N1 + N2	15
-	Subtraction	N1 - N2	5
*	Multiplication	N1 * N2	50
/	Division	N1 / N2	2
%	Modulus (Remainder)	N1 % N2	0
++	Increment	++N2	6
--	Decrement	--N1	9

Assignment Operators

Used to assign values to variables, often combined with an arithmetic or bitwise operation.

Operator	Example	Equivalent To
=	x = 9	x = 9
+=	x += 9	x = x + 9
-=	x -= 9	x = x - 9
*=	x *= 9	x = x * 9
/=	x /= 9	x = x / 9
%=	x %= 9	x = x % 9
&=	x &= 9	x = x & 9
|=	x |= 9	x = x | 9
^=	x ^= 9	x = x ^ 9
>>=	x >>= 9	x = x >> 9

Comparison Operators

Used to compare two values and return a boolean result (true or false, often represented as 1 or 0). An example is != (Not equal). (8 != 5) evaluates to true (1).

Logical Operators

Used to combine conditional statements.

Operator	Name	Description	Example
&&	Logical AND	Returns true if both statements are true.	a < 8 && a < 12
|	Logical OR	Returns true if one of the statements is true.	x < 5 | x > 10
!	Logical NOT	Reverses the result; returns false if the result is true.	!(a < 7 && a < 15)

Mathematical Functions (<cmath>)

• floor(x): Rounds a number down to the nearest integer.
  • floor(4.99) results in 4
  • floor(-3.7) results in -4

---

2. Conditional Statements

if Statement

Executes a block of code if a specified condition is true.

if...else Statement

Executes one block of code if a condition is true and another block if it is false.

if...else if...else Statement

Specifies a new condition to test if the first condition is false.

switch Statement

Tests the value of a variable against a list of predefined constant values (case).

• Purpose: Selects one of many code blocks to be executed.
• break Keyword: Exits the switch block. If omitted, execution "falls through" to the next case.
• default Keyword: Specifies the code to run if there is no case match.

---

3. Loops

while Loop

Executes a block of code as long as a specified condition is true. The condition is checked before the loop body is executed.

• When to use: Recommended when the number of iterations is unknown.

do...while Loop

A variant of the while loop where the code block is executed at least once, and the condition is checked after the loop body.

• When to use: Recommended when the iteration count is unknown and the body must run at least once.

for Loop

Executes a block of code a known number of times. It consists of three parts: initialization, condition, and increment/decrement.

• When to use: Recommended when the number of iterations is known.

Nested Loops

A loop placed inside another loop. The inner loop executes fully for each iteration of the outer loop.

• Example Use Case: Printing patterns, like a triangle of stars, where the outer loop controls the rows and the inner loop controls the columns (stars per row).