Lesson 3: Operators and Expressions

🎯 Lesson Objective

To understand different types of operators in Python and how to use them in expressions to perform calculations or logic.

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🧠 1. What Are Operators?

Operators are special symbols that perform operations on variables and values.
Expressions are combinations of variables, operators, and values that produce a result.

Example:

x = 10
y = 5
result = x + y
print(result)  # Output: 15

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⚙️ 2. Types of Operators

A. Arithmetic Operators

Used for mathematical operations.

Operator	Description	Example	Output
+	Addition	5 + 3	8
-	Subtraction	5 - 3	2
*	Multiplication	5 * 3	15
/	Division	10 / 3	3.3333
//	Floor Division	10 // 3	3
%	Modulus (Remainder)	10 % 3	1
**	Exponentiation	2 ** 3	8

Example:

a, b = 10, 3
print(a + b, a - b, a * b, a / b, a // b, a % b, a ** b)

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B. Comparison Operators

Used to compare two values. They return either True or False.

Operator	Meaning	Example	Output
==	Equal to	5 == 5	True
!=	Not equal to	5 != 3	True
>	Greater than	7 > 4	True
<	Less than	3 < 5	True
>=	Greater or equal	5 >= 5	True
<=	Less or equal	4 <= 3	False

Example:

x, y = 10, 20
print(x > y)  # False
print(x != y) # True

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C. Logical Operators

Used to combine conditional statements.

Operator	Description	Example	Output
and	True if both are true	x > 5 and y < 30	True
or	True if one is true	x > 15 or y < 30	True
not	Reverses the result	not(x > 5)	False

Example:

x, y = 10, 20
print(x > 5 and y < 25)  # True
print(x > 15 or y < 25)  # True
print(not(x > 5))        # False

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D. Assignment Operators

Used to assign values to variables.

Operator	Example	Equivalent To
=	x = 10	x = 10
+=	x += 2	x = x + 2
-=	x -= 3	x = x - 3
*=	x *= 2	x = x * 2
/=	x /= 2	x = x / 2

Example:

x = 5
x += 3
print(x)  # Output: 8

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E. Bitwise Operators (Advanced)

Used to perform operations on binary numbers.

Operator	Description	Example	Output
&	AND	5 & 3	1
`	`	OR	`5
^	XOR	5 ^ 3	6
~	NOT	~5	-6
<<	Left shift	5 << 1	10
>>	Right shift	5 >> 1	2

Example:

a, b = 5, 3
print(a & b, a | b, a ^ b)

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🧩 3. Expressions

An expression is a combination of values, variables, and operators that evaluates to a result.

Example:

x = 10
y = 5
z = (x + y) * 2
print(z)  # Output: 30

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🧠 4. Practice Ideas

1. Write a Python program to calculate the area of a rectangle using variables.
2. Check if a number is positive and even using comparison and logical operators.
3. Create a program that swaps two variables using assignment operators.

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