Basic Operators

Basic Operators

This section explains how to use basic operators in Python.
Arithmetic Operators

Just as any other programming languages, the addition, subtraction, multiplication, and division operators can be used with numbers.
Try to predict what the answer will be. Does python follow order of operations?

       
number = 1 + 2 * 3 / 4.0
print number
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Another operator available is the modulo (%) operator, which returns the integer remainder of the division. dividend % divisor = remainder.
remainder = 11 % 3
print remainder
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Using two multiplication symbols makes a power relationship.
         

squared = 7 ** 2
cubed = 2 ** 3
print squared
print cubed

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Using Operators with Strings

Python supports concatenating strings using the addition operator:
helloworld = "hello" + " " + "world"
print helloworld
lotsofhellos = "hello" * 10
print lotsofhellos
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Operator Description Example
+, - Addition, Subtraction 10 -3
*, % Multiplication, Modulo 27 % 7
Result: 6
/ Division
This operation results in different results for Python 2.x (like floor division) and Python 3.x Python3:
>>> 10  / 3
3.3333333333333335
and in Python 2.x:
>>> 10  / 3
3
// Truncation Division (also known as floordivision or floor division)
The result of this division is the integral part of the result, i.e. the fractional part is truncated, if there is any.
It works both for integers and floating-point numbers, but there is a difference in the type of the results: If both the divident and the divisor are integers, the result will be also an integer. If either the divident or the divisor is a float, the result will be the truncated result as a float.
>>> 10 // 3
3
If at least one of the operands is a float value, we get a truncated float value as the result.
>>> 10.0 // 3
3.0
>>>
A note about efficiency:
The results of int(10 / 3) and 10 // 3 are equal. But the "//" division is more than two times as fast! You can see this here:
In [9]: %%timeit
for x in range(1, 100):
    y = int(100 / x)
   ...:
100000 loops, best of 3: 11.1 μs per loop

In [10]: %%timeit
for x in range(1, 100):
    y = 100 // x
   ....:
100000 loops, best of 3: 4.48 μs per loop
+x, -x Unary minus and Unary plus (Algebraic signs) -3
~x Bitwise negation ~3 - 4
Result: -8
** Exponentiation 10 ** 3
Result: 1000
or, and, not Boolean Or, Boolean And, Boolean Not (a or b) and c
in "Element of" 1 in [3, 2, 1]
<, <=, >, >=, !=, == The usual comparison operators 2 <= 3
|, &, ^ Bitwise Or, Bitwise And, Bitwise XOR 6 ^ 3
<<, >> Shift Operators 6 << 3

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