Day -2 : Mastering basics of Python

Operators in python

1. Arithmetic Operators

Used for basic mathematical calculations.

• + (Addition): Adds two numbers.
  
  Example: 5 + 3 → 8

• - (Subtraction): Subtracts the second number from the first.
  
  Example: 5 - 3 → 2

• * (Multiplication): Multiplies two numbers.
  
  Example: 5 * 3 → 15

• / (Division): Divides the first number by the second, returning a float.
  
  Example: 5 / 2 → 2.5

• // (Floor Division): Divides and rounds down to the nearest integer.
  
  Example: 5 // 2 → 2

• % (Modulus): Returns the remainder of the division.
  
  Example: 5 % 2 → 1

• ` (Exponentiation):** Raises the first number to the power of the second.
Example: 5 ** 2 → 25`
  

# Arithmetic Operators
a = 10
b = 3

print("Addition:", a + b)        # 13
print("Subtraction:", a - b)     # 7
print("Multiplication:", a * b)  # 30
print("Division:", a / b)        # 3.333...
print("Floor Division:", a // b) # 3
print("Modulus:", a % b)         # 1
print("Exponentiation:", a ** b) # 1000

2. Assignment Operators

Used to assign values to variables.

• = (Assign): Assigns a value to a variable.
  
  Example: x = 5

• += (Add and Assign): Adds a value and reassigns.
  
  Example: x += 3 → x = x + 3

• -= (Subtract and Assign): Subtracts a value and reassigns.
  
  Example: x -= 3 → x = x - 3

• *= (Multiply and Assign): Multiplies a value and reassigns.
  
  Example: x *= 3 → x = x * 3

• /= (Divide and Assign): Divides a value and reassigns.
  
  Example: x /= 3 → x = x / 3

• //= (Floor Divide and Assign): Floor divides and reassigns.
  
  Example: x //= 3 → x = x // 3

• %= (Modulus and Assign): Applies modulus and reassigns.
  
  Example: x %= 3 → x = x % 3

• `= (Exponentiate and Assign):** Raises to a power and reassigns.
Example: x *= 2 → x = x * 2`
  

# Assignment Operators
x = 5
print("Initial value:", x)       # 5

x += 3
print("After += 3:", x)          # 8

x -= 2
print("After -= 2:", x)          # 6

x *= 4
print("After *= 4:", x)          # 24

x /= 3
print("After /= 3:", x)          # 8.0

x //= 2
print("After //= 2:", x)         # 4.0

x %= 3
print("After %= 3:", x)          # 1.0

x **= 2
print("After **= 2:", x)         # 1.0

3. Comparison Operators

Used to compare two values.

• == (Equal to): Checks if two values are equal.
  
  Example: 5 == 5 → True

• != (Not Equal to): Checks if two values are not equal.
  
  Example: 5 != 3 → True

• > (Greater than): Checks if the first value is greater than the second.
  
  Example: 5 > 3 → True

• < (Less than): Checks if the first value is less than the second.
  
  Example: 3 < 5 → True

• >= (Greater than or Equal to): Checks if the first value is greater than or equal to the second.
  
  Example: 5 >= 5 → True

• <= (Less than or Equal to): Checks if the first value is less than or equal to the second.
  
  Example: 3 <= 5 → True
  

# Comparison Operators
a = 10
b = 5

print("Equal:", a == b)          # False
print("Not Equal:", a != b)      # True
print("Greater than:", a > b)    # True
print("Less than:", a < b)       # False
print("Greater or Equal:", a >= b) # True
print("Less or Equal:", a <= b)  # False

4. Logical Operators

Used for combining conditions.

• and: Returns True if both conditions are true.
  
  Example: (5 > 3) and (4 > 2) → True

• or: Returns True if at least one condition is true.
  
  Example: (5 > 3) or (2 > 4) → True

• not: Reverses the truth value.
  
  Example: not(5 > 3) → False
  

# Logical Operators
a = True
b = False

print("AND:", a and b)           # False
print("OR:", a or b)             # True
print("NOT a:", not a)           # False
print("NOT b:", not b)           # True

5. Bitwise Operators

Operate on binary representations of numbers.

• &: Performs bitwise AND.
  
  Example: 5 & 3 → 1

• |: Performs bitwise OR.
  
  Example: 5 | 3 → 7

• ^: Performs bitwise XOR.
  
  Example: 5 ^ 3 → 6

• ~: Performs bitwise NOT.
  
  Example: ~5 → -6

• <<: Shifts bits to the left.
  
  Example: 5 << 1 → 10

• >>: Shifts bits to the right.
  
  Example: 5 >> 1 → 2
  

# Bitwise Operators
a = 5  # Binary: 0101
b = 3  # Binary: 0011

print("Bitwise AND:", a & b)     # 1 (Binary: 0001)
print("Bitwise OR:", a | b)      # 7 (Binary: 0111)
print("Bitwise XOR:", a ^ b)     # 6 (Binary: 0110)
print("Bitwise NOT (~a):", ~a)   # -6
print("Left Shift:", a << 1)     # 10 (Binary: 1010)
print("Right Shift:", a >> 1)    # 2 (Binary: 0010)

6. Membership Operators

Check if a value is present in a sequence.

• in: Returns True if the value is in the sequence.
  
  Example: 'a' in 'apple' → True

• not in: Returns True if the value is not in the sequence.
  
  Example: 'z' not in 'apple' → True
  

# Membership Operators
sequence = [1, 2, 3, 4, 5]

print("3 in sequence:", 3 in sequence)       # True
print("6 in sequence:", 6 in sequence)       # False
print("6 not in sequence:", 6 not in sequence) # True

7. Identity Operators

Check if two variables reference the same object.

• is: Returns True if two variables point to the same object.
  
  Example: x is y

• is not: Returns True if two variables point to different objects.
  
  Example: x is not y
  

# Identity Operators
a = [1, 2, 3]
b = a
c = [1, 2, 3]

print("a is b:", a is b)         # True (same object)
print("a is c:", a is c)         # False (different objects)
print("a is not c:", a is not c) # True

8. Ternary Operator

The ternary operator allows a shorthand for if-else statements.

# Ternary Operator
a, b = 10, 20

max_value = a if a > b else b
print("Maximum value:", max_value)  # 20

9. Walrus Operator (:=)

Introduced in Python 3.8, the walrus operator allows assignment inside expressions.

# Walrus Operator (Python 3.8+)
data = [1, 2, 3, 4, 5]

if (n := len(data)) > 3:
    print("Length is greater than 3:", n)  # 5

10. Enumerate with Loops

The enumerate() function returns both the index and the value of each item in an iterable.

# Enumerate with Loops
colors = ["red", "green", "blue"]
for index, color in enumerate(colors):
    print(f"{index}: {color}")