We will briefly take a look at the operators and their usage, depicted in the following table.
You can evaluate the expressions given in the examples using the interpreter interactively. For example, to test the expression 2 + 3, use the interactive Python interpreter prompt:
>>> 2 + 3 5 >>> 3 * 5 15 >>>
Table 5.1. Operators and their usage
Operator | Name | Explanation | Examples |
---|---|---|---|
+ | Plus | Adds the two objects | 3 + 5 gives 8. 'a' + 'b' gives 'ab'. |
- | Minus | Either gives a negative number or gives the subtraction of one number from the other. | -5.2 returns a negative number. 50 - 24 gives 26. |
* | Multiply | Gives the multiplication of the two numbers or returns the string repeated by that many times. | 2 * 3 gives 6. 'la' * 3 gives 'lalala'. |
** | Power | Returns x to the power of y | 3 ** 4 gives 81 (i.e. 3 * 3 * 3 * 3) |
/ | Divide | Divides x by y | 4/3 gives 1 since division of integers gives an integer. 4.0/3 or 4/3.0 gives 1.3333333333333333. |
// | Floor Division | Returns the floor of the quotient | 4 // 3.0 gives 1.0 |
% | Modulo | Returns remainder of the division | 8%3 gives 2. -25.5 % 2.25 gives 1.5 . |
<< | Left Shift | Shifts the bits of the number to the left by the number of bits specified. Each number is represented in memory by bits (binary digits i.e. 0 and 1) | 2 << 2 gives 8. 2 is represented by 10 in bits. Left shifting by 2 bits gives 1000 which represents the decimal 8. |
>> | Right Shift | Shifts the bits of the number to the right by the number of bits specified. | 11 >> 1 gives 5. 11 is represented in bits by 1011 which when right shifted by 1 bit gives 101 which is nothing but decimal 5. |
& | Bit-wise AND | Bitwise AND of the numbers | 5 & 3 gives 1. |
| | Bit-wise OR | Bitwise OR of the numbers | 5 | 3 gives 7. |
^ | Bit-wise XOR | Bitwise XOR of the numbers | 5 ^ 3 gives 6 |
~ | Bit-wise invert | The bit-wise inversion of x is -(x+1) | ~5 gives -6 |
< | Less Than | Returns whether x is less than y. All comparison operators return 1 for true and 0 for false. This is equivalent to the special variables True and False respectively. Note the capitalization of these variables' names. | 5 < 3 gives 0 and 3 < 5 gives 1 i.e. 5 < 3 gives False and 3 < 5 gives True. Comparisons can be chained arbitrarily. 3 < 5 < 7 gives True. |
> | Greater Than | Returns whether x is greater than y | 5 > 3 returns True. If both operands are numbers, they are first converted to a common type. Otherwise, it always returns False. |
<= | Less Than or Equal To | Returns whether x is less than or equal to y | x = 3; y = 6; x <= y returns True. |
>= | Greater Than or Equal To | Returns whether x is greater than or equal to y | x = 4; y = 3; x >= 3 returns True. |
== | Equal To | Compares if the objects are equal | x = 2; y = 2; x == y returns True. x = 'str'; y = 'stR'; x == y returns False. x = 'str'; y = 'str'; x == y returns True. |
!= | Not Equal To | Compares if the objects are not equal | x = 2; y = 3; x != y returns True |
not | Boolean NOT | If x is True, it returns False. If x is False, it returns True | x = True; not y returns False. |
and | Boolean AND | x and y returns False if x is False, else it returns evaluation of y | 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 has to be False. This is called short-circuit evaluation. |
or | Boolean OR | If x is True, it returns x else it returns evaluation of y | x = True; y = False; x or y returns True. Short-circuit evaluation applies here as well. |