operators
source: Python Tutorial/operators.md
Operators are used to perform operations on values and variables. The Python operators are classified into seven different categories:
- Arithmetic operators
- Assignment operators
- Comparison operators
- Logical operators
- Identity operators
- Membership operators
- Bitwise operators
- Arithmetic Operators
Arithmetic operators
Arithmetic operators are used to perform simple mathematical operations on numeric values (except complex).
| Operator | Meaning | Example |
|---|---|---|
| + | Addition | x + y |
| – | Subtraction | x – y |
| * | Multiplication | x * y |
| / | Division | x / y |
| % | Modulus | x % y |
| ** | Exponentiation | x ** y |
| // | Floor division | x // y |
Here are some examples:
x = 6
y = 2
# addition
print(x + y) # 8
# subtraction
print(x - y) # 4
# multiplication
print(x * y) # 12
# division
print(x / y) # 3
# modulus
print(x % y) # 0
# exponentiation
print(x ** y) # 36
# floor division
print(x // y) # 3
For additional numeric operations see the math module
Assignment Operators
Assignment operators are used to assign new values to variables.
| Operator | Meaning | Example | Equivatent to |
|---|---|---|---|
| = | Assignment | x = 3 | x = 3 |
| += | Addition assignment | x += 3 | x = x + 3 |
| -= | Subtraction assignment | x -= 3 | x = x – 3 |
| *= | Multiplication assignment | x *= 3 | x = x * 3 |
| /= | Division assignment | x /= 3 | x = x / 3 |
| %= | Modulus assignment | x %= 3 | x = x % 3 |
| //= | Floor division assignment | x //= 3 | x = x // 3 |
| **= | Exponentiation assignment | x **= 3 | x = x ** 3 |
| &= | Bitwise AND assignment | x &= 3 | x = x & 3 |
| = | Bitwise OR assignment | x |= 3 | x = x | 3 |
| ^= | Bitwise XOR assignment | x ^= 3 | x = x ^ 3 |
| »= | Bitwise right shift assignment | x »= 3 | x = x » 3 |
| «= | Bitwise left shift assignment | x «= 3 | x = x « 3 |
Comparison Operators
Comparison operators are used to compare two values.
| Operator | Meaning | Example |
|---|---|---|
| == | Equal to | x == y |
| != | Not equal to | x != y |
| > | Greater than | x > y |
| < | Less than | x < y |
| >= | Greater than or equal to | x >= y |
| <= | Less than or equal to | x <= y |
Here are some examples:
x = 6
y = 2
# equal to
print(x == y) # False
# not equal to
print(x != y) # True
# greater than
print(x > y) # True
# less than
print(x < y) # False
# greater than or equal to
print(x >= y) # True
# less than or equal to
print(x <= y) # False
Logical Operators
Logical operators are used to join two or more conditions.
| Operator | Description | Example |
|---|---|---|
| and | Returns True if both statements are true | x > 0 and y < 0 |
| or | Returns True if one of the statements is true | x > 0 or y < 0 |
| not | Reverse the result, returns False if the result is true | not (x > 0 and y < 0) |
Here are some examples:
x = 2
y = -2
# and
print(x > 0 and y < 0) # True
# or
print(x > 0 or y < 0) # True
# not
print(not(x > 0 and y < 0)) # False
Identity Operators
Identity operators are used to check if two objects point to the same object, with the same memory location.
| Operator | Description | Example |
|---|---|---|
| is | Returns true if both variables are the same object | x is y |
| is not | Returns true if both variables are not the same object | x is not y |
Here are some examples:
x = [1, 2, 3]
y = [1, 2, 3]
# is
print(x is y) # False
# is not
print(x is not y) # True
Membership Operators
Membership operators are used to check if a specific item is present in a sequence (such as a string, tuple, list, or range) or a collection (such as a dictionary, set, or frozen set).
| Operator | Description | Example |
|---|---|---|
| in | Returns True if a value is present in the sequence | x in y |
| not in | Returns True if a value is not present in the sequence | x not in y |
Here are some examples:
L = ['red', 'green', 'blue']
# in
print('red' in L) # True
# not in
print('yellow' not in L) # True
Bitwise Operators
Binary operators are used to perform bit-level operations on (binary) numbers.
| Operator | Meaning | Example |
|---|---|---|
| & | AND | x & y |
| | OR | x | y |
| ^ | XOR | x ^ y |
| ~ | NOT | ~x |
| « | Left shift | x « 2 |
| » | Right shift | x » 2 |
Here are some examples:
x = 0b1100
y = 0b1010
# and
print(bin(x & y)) # 0b1000
# or
print(bin(x | y)) # 0b1110
# xor
print(bin(x ^ y)) # 0b0110
# not
print(bin(~x)) # -0b1101
# shift 2 bits left
print(bin(x << 2)) # 0b1100
# shift 2 bits right
print(bin(x >> 2)) # 0b0011
Operator Precedence (Order of Operations)
In Python, every operator is assigned a precedence. Operator Precedence determines which operations are performed before which other operations.
Operators of highest precedence are performed first. Any operators of equal precedence are performed in left-to-right order.
| Precedence | Operator | Description |
|---|---|---|
| lowest precedence | or | Boolean OR |
| and | Boolean AND | |
| not | Boolean NOT | |
| ==, ! =, <, <=, >, >=, | ||
| is, is not | comparisons, identity | |
| | bitwise OR | |
| ^ | bitwise XOR | |
| & | bitwise AND | |
| «, » | bitwise shis | |
| +, – | addition, subtraction | |
| *, /, //, % | multiplication, division, floor division, modulo | |
| +x, -x, ~x | unary positive, unary negation, bitwise negation | |
| highest precedence | ** | exponentiation |