Operators¶

Arithmetic Operators¶

1. The Basic Operators¶

Addition (+)¶

The addition operator adds two operands together. In many programming languages, if the operands are strings instead of numbers, this operator performs concatenation (joining them together).

• Mathematical Formula: A + B
• Example:

  result = 5 + 3  # result is 8

Subtraction (-)¶

The subtraction operator subtracts the right operand from the left operand. It can also be used as a unary operator to indicate a negative number (e.g., -5).

• Mathematical Formula: A - B
• Example:

  result = 10 - 4  # result is 6
  

Multiplication (*)¶

The multiplication operator multiplies two operands. In programming, the asterisk (*) is universally used instead of the traditional x to avoid confusion with variables.

• Mathematical Formula: A * B
• Example:

  result = 7 * 6  # result is 42
  

Division (/)¶

The division operator divides the left operand (dividend) by the right operand (divisor). Note: In some strictly typed languages (like C or Java), dividing two integers might automatically drop the decimal. However, in modern languages like Python or JavaScript, standard division always results in a floating-point number (a decimal).

• Mathematical Formula: A / B
• Example:

  result = 20 / 4  # result is 5.0
  result = 5 / 2   # result is 2.5
  

2. Specialized Arithmetic Operators¶

Modulo / Remainder (%)¶

The modulo operator divides the left operand by the right operand, but instead of returning the quotient, it returns the remainder. This is exceptionally useful in programming for determining if a number is even or odd, keeping numbers within a certain bounds (like a clock face), or parsing data.

• Mathematical Concept: Remainder of A / B
• Example:

result = 10 % 3  # result is 1 (because 10 divided by 3 is 9, with 1 left over)
is_even = 14 % 2 # result is 0 (no remainder means it's an even number)

Exponentiation (**)¶

The exponentiation operator raises the left operand (base) to the power of the right operand (exponent).

• Mathematical Concept: A**B (A to the power of B)
• Example:

  result = 2 ** 3  # result is 8 (2 * 2 * 2)
  

Floor Division / Integer Division (//)¶

Floor division divides the two operands and then automatically rounds the result down to the nearest whole integer. It effectively chops off the decimal portion.

• Mathematical Concept: ⌊A / B⌋
• Example:

  result = 10 // 3  # result is 3 (10 / 3 is 3.333..., rounded down to 3)
  result = 15 // 4  # result is 3 (15 / 4 is 3.75, rounded down to 3)
  

Python Assignment Operators¶

Assignment operators are used to assign values to variables in Python.

List of Assignment Operators¶

Here is a complete list of Python assignment operators, showing how they are used and what they are equivalent to:

The Walrus Operator (:=)¶

Introduced in Python 3.8, the := operator is officially known as the assignment expression, but is commonly called the walrus operator because it resembles the eyes and tusks of a walrus on its side.

It allows you to assign a value to a variable as part of a larger expression.

Example:¶

Why is it useful? It helps you avoid writing the same expression twice, often making loops and if statements much cleaner.

# Without the walrus operator
word = "Hello"
n = len(word)
if n > 3:
    print(f"The word has {n} letters.")

# With the walrus operator
word = "Hello"
if (n := len(word)) > 3:
    print(f"The word has {n} letters.")

note - Summary of the rule * Use = when you just need to store a value for later. * Use := when you need to store a value and immediately feed that value into an if statement, while loop, or list comprehension on the exact same line.

Membership Operators¶

Membership operators are used to test if a sequence is presented in an object:

Operator - "in" , Returns True if a sequence with the specified value is present in the object.

Operator - "not in" Returns True if a sequence with the specified value is not present in the object.

x = ["apple", "banana"]

print("banana" in x)

# returns True because a sequence with the value "banana" is in the list

x = ["apple", "banana"]

print("pineapple" not in x)

# returns True because a sequence with the value "pineapple" is not in the list