Operators

We will briefly take a look at the operators and their usage:

Tip

You can evaluate the expressions given in the examples using the interpreter interactively. For example, to test the expression2 + 3, use the interactive Python interpreter prompt:

>>> 2 + 3
5
>>> 3 * 5
15
>>>

Table 5.1. Operators and their usage

Operator Name

 

+ Plus

 

Explanation

 

Adds the two objects

 

- Minus

 

* Multiply

 

** Power

/ Divide Either gives a negative number or gives the subtraction of one number from the other

Gives the multiplication of the two numbers or returns the string repeated that many times.

Returns x to the power of y

 

Divide x by y

 

Examples

 

3 + 5 gives8.'a' + 'b' gives'ab'.

-5.2 gives a negative number. 50 - 24 gives26.

2 * 3 gives6.'la' * 3 gives'lalala'.

 

3 ** 4 gives81 (i.e.3 * 3 * 3 * 3)

4/3 gives1 (division of integers gives an integer). 4.0/3 or 4/3.0 gives 1.33333333333333 33

// Floor Division

% Modulo Returns the floor of the quotient

Returns the remainder of the division

 

<< Left Shift

>> Right Shift Shifts the bits of the number to the left by the number of bits specified. (Each number is represented in memory by bits or binary digits i.e. 0 and 1)

Shifts the bits of the number to the right by the number of bits specified.

& Bitwise AND

 

| Bit-wise OR

 

^ Bit-wise XOR ~ Bit-wise invert

 

< Less Than

> Greater Than Bitwise AND of the numbers

Bitwise OR of the numbers
5 ^ 3 gives6

The bit-wise inversion of x is -(x+1)

Returns whether x is less than y. All comparison operators return 1 for true and 0 for false. This is equivalent to the special variablesTrue and False respectively. Note the capitalization of these variables' names.

Returns whether x is greater than y

 

<= Less Than or Equal To

 

>= Greater Than or Equal To

== Equal To
Returns whether x is less than or equal to y

Returns whether x is greater than or equal to y Compares if the objects are equal

 

4 // 3.0 gives1.0

8%3 gives 2. -
25.5%2.25 gives1.5 .
2 << 2 gives8. 2 is represented by 10 in bits. Left shifting by 2 bits gives 1000 which represents the decimal8.

11 >> 1 gives5 11 is represented in bits by
1011 which when right shifted by 1 bit gives
101 which is nothing but decimal5.

5 & 3 gives1.

 

5 | 3 gives7
~5 gives-6.

5 < 3 gives 0 (i.e. False) and 3 < 5 gives 1 (i.e. True). Comparisons can be chained arbitrarily: 3 < 5 < 7 givesTrue.

5 < 3 returnsTrue. If both operands are numbers, they are first converted to a common type. Otherwise, it always returnsFalse. x = 3; y = 6; x <= y returnsTrue.

x = 4; y = 3; x >= 3 returnsTrue.

x = 2; y = 2; x == y returns True. x = 'str'; y = 'stR'; x == y returns False. x = 'str'; y = 'str'; x == y re

!= Not Equal To

 

not Boolean NOT

and Boolean AND Compares if the objects are not equal

If x is True, it returns False. If x isFalse, it returnsTrue.

x and y returns False if x is False, else it returns evaluation of y

or Boolean OR If x is True, it returns True, else it returns evaluation of y

 

turnsTrue.

 

x = 2; y = 3; x != y returnsTrue. x = True; not y returnsFalse.

x = False; y = True; x and y returns False since x is False. In this case, Python will not evaluate y since it knows that the value of the expression will has to be false (since x is False). This is called short-circuit evaluation.

x = True; y = False; x or y returns True. Short-circuit evaluation applies here as well.