Operators

Each operator in python has a corresponding magic method of corresponding class. When you use operator, it calls the magic method under the hood. In python, some operators are symbols and some are text.

Assignment operators

= to assign value to a variable

Arithmatic operators

used for arithmatic operations

• + to addition
• - to subtraction
• * to multiplication
• / to division
• % to modulo
• // to floor division
• ** to exponentiation

Comparison operators

• ==
• !=
• >
• <
• >=
• <=

Logical operators

return boolean value, True or False

• and: check if both operands are true
• or: check if either operand is true
• not: check if operand is false
• in: check if element is present in a sequence
• not in: check if element is not present in a sequence
• is: check if two objects are the same object
• is not: check if two objects are different object
• |: check if either operand is true
• &: check if both operands are true
• ^: check if either operand is true

WARNING

del is not an operator, it is a statement to delete elements from a list and dictionary.

my_guitar = {
    'brand': 'Ibanez',
    'price': 10000,
}

print('color' not in my_guitar)
# True

Falsy values

values that evaluate to False in boolean context. bool(value) return False. In python, the following values are falsy.

• False
• None
• 0, 0.0, 0j (int, float, complex)
• '' (empty string)
• [] (empty list)
• {} (empty dictionary)
• set() (empty set)
• () (empty tuple)
• range(0) (empty range)

short circuit operation

and operator

If left operand is false, right operand is not evaluated. Goal is here to find 1st falsy value.

is_new = False
price = 1000
print(is_new and price < 1500)
# False (price is not evaluated)

or operator

If left operand is true, right operand is not evaluated. Goal is to find 1st truthy value.

name = 'Kibria'
age = 41

print(name == 'Kibria' or age > 40)
# True (age is not evaluated)

Unary operators

has just one operand. they are prefix operator.

• +: use to convert a number to positive, boolean to integer
• -: use to negate a number
• ~: use to invert a number
• not: use to negate a boolean
• abs: use to get absolute value of a number

is_new = True
print(+is_new)
# 1

num_1 = 5
print(-num_1)
# -5

name = ''
print(not name)
# True
name = 'Kibria'
print(not name)
# False
print(not not name)
# True

num_4 = 23.98
num_5 = -23.98
print(abs(num_4))
# 23.98
print(abs(num_5))
# 23.98

Binary operators

has 2 operands. They are infix (between operands) operator.

• a = 5
• a + b
• a += 4
• a == b
• a and b