2.3 Basic Operators

Operators are essential components in Python that allow you to perform operations on variables and values. Python supports a variety of operators, and they can be classified into different categories, such as arithmetic, comparison, logical, and assignment operators. This section covers the basic operators that you will frequently use in Python programming.

1. Arithmetic Operators

These operators are used to perform mathematical operations.

Example:

a = 5
b = 3

print(a + b)  # 8 (addition)
print(a - b)  # 2 (subtraction)
print(a * b)  # 15 (multiplication)
print(a / b)  # 1.666 (division)
print(a // b) # 1 (floor division)
print(a % b)  # 2 (modulus)
print(a ** b) # 125 (exponentiation)

• +: Adds two numbers.
• -: Subtracts the second number from the first.
• *: Multiplies two numbers.
• /: Divides the first number by the second, returning a float.
• //: Performs integer (floor) division, discarding the fractional part.
• %: Returns the remainder after division (modulo).
• **: Raises the first number to the power of the second.

2. Comparison Operators

Comparison operators are used to compare two values. These operators return a Boolean value (True or False).

Example:

a = 5
b = 3

print(a == b)  # False (not equal)
print(a != b)  # True (not equal)
print(a > b)   # True (a is greater than b)
print(a < b)   # False (a is not less than b)
print(a >= b)  # True (a is greater than or equal to b)
print(a <= b)  # False (a is not less than or equal to b)

• ==: Checks if two values are equal.
• !=: Checks if two values are not equal.
• >: Checks if the left value is greater than the right value.
• <: Checks if the left value is less than the right value.
• >=: Checks if the left value is greater than or equal to the right value.
• <=: Checks if the left value is less than or equal to the right value.

3. Logical Operators

Logical operators are used to combine conditional statements and evaluate the conditions.

Example:

a = 5
b = 3

print(a > b and b < 4)  # True (both conditions are true)
print(a > b or b > 4)   # True (one condition is true)
print(not(a > b))       # False (negation)

• and: Returns True only if both conditions are True.
• or: Returns True if at least one condition is True.
• not: Reverses the truth value of the condition.

4. Assignment Operators

Assignment operators are used to assign values to variables.

Example:

a = 10
a += 5  # a = a + 5 -> a = 15
a -= 3  # a = a - 3 -> a = 12
a *= 2  # a = a * 2 -> a = 24
print(a)

• =: Assigns a value to a variable.
• +=: Adds the value and assigns the result to the variable.
• -=: Subtracts the value and assigns the result to the variable.
• *=: Multiplies the value and assigns the result to the variable.
• /=: Divides the value and assigns the result to the variable.
• //=: Floor divides the value and assigns the result to the variable.
• %=: Takes the modulus and assigns the result to the variable.
• **=: Raises the value to the power and assigns the result to the variable.

5. Membership Operators

These operators are used to check if a value or variable is found in a sequence (like a list, tuple, or string).

Example:

fruits = ["apple", "banana", "cherry"]
print("banana" in fruits)  # True
print("grape" not in fruits)  # True

• in: Returns True if the value is found in the sequence.
• not in: Returns True if the value is not found in the sequence.

6. Identity Operators

These operators are used to compare the memory locations of two objects.

Example:

a = [1, 2, 3]
b = [1, 2, 3]
c = a

print(a is b)       # False (a and b are different objects)
print(a is c)       # True (a and c point to the same object)

• is: Returns True if both variables point to the same object.
• is not: Returns True if both variables do not point to the same object.

Summary:

• Arithmetic operators are used for mathematical calculations.
• Comparison operators are used to compare two values.
• Logical operators combine multiple conditions to evaluate expressions.
• Assignment operators are used to assign values to variables, and can also be used with arithmetic operations.
• Membership operators check if a value is present or absent from a sequence.
• Identity operators check if two variables point to the same memory location or object.

These operators are essential tools for performing tasks, making decisions, and manipulating data in Python.