Concise Python Tutorials

Brief introduction

Most of the statements you write (logical rows) contain an expression. A simple expression example is 2 + 3. An expression can be decomposed into operators and operands.

The function of an operator is to accomplish something that is represented by symbols such as + or other specific keywords. Operators require data for operations, and such data is called operands. In this example, 2 and 3 are operands.

Operator

We'll take a quick look at the operators and their usage:

Skills

You can interactively use an interpreter to compute the expression given in the example. For example, to test expression 2 + 3, use an interactive Python interpreter with a prompt:

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

Table 5.1 operators and their usage

Operator	Name	Description	Example
+	Add	Add two objects	3 + 5 gets 8. ' A ' + ' B ' gets ' ab '.
-	Reducing	Get negative numbers or a number minus another number	-5.2 Gets a negative number. 50-24 get 26.
*	By	Multiply two numbers or return a string that is repeated several times	2 * 3 get 6. ' La ' * 3 gets ' Lalala '.
**	Power	Returns the Y-power of X	3 * * 4 gets 81 (ie 3 * 3 * 3 * 3)
/	Except	x divided by Y	4/3 gets 1 (the integer division gets the integer result). 4.0/3 or 4/3.0 get 1.3333333333333333
//	Take the Divide	The integer part of the return quotient	4//3.0 gets 1.0
%	Take the mold	Returns the remainder of a division	8%3 got 2. -25.5%2.25 got 1.5.
<<	Move left	Shifts a number of bits to the left a certain number (each number in memory is represented as a bit or binary number, i.e. 0 and 1)	2 << 2 get 8. --2 is expressed as 10 by bit
>>	Move right	Move a number of bits to the right by a certain number	One >> 1 get 5. --11 is expressed as 1011 by bit, 1 bits to the right and 101, or 5 in decimal.
&	Bitwise AND	The bitwise of number and	5 & 3 Get 1.
|	by bit or	Number of bitwise OR	5 | 3 Get 7.
^	Per-bitwise XOR OR	The bitwise XOR of the number or	5 ^ 3 Get 6
~	Flip by bit	The bit flip of X is-(x+1)	~5 got 6.
<	Less than	Returns whether x is less than Y. All comparison operators return 1 to represent true, and 0 to represent false. This is equivalent to the special variable true and false respectively. Note that these variable names are capitalized.	5 < 3 returns 0 (that is, false) and 3 < 5 returns 1 (that is, true). Comparisons can be any connection: 3 < 5 < 7 returns TRUE.
>	Greater than	Returns whether x is greater than Y	5 > 3 returns TRUE. If two 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 >= y returns True.
==	Equals	Compare objects for Equality	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	Compare two objects for unequal	x = 2; y = 3; X!= y returns True.
Not	Boolean "Non"	Returns False if X is true. If x is False, it returns true.	x = True; Not Y returns false.
and	Boolean "and"	If x is False,x and Y returns false, it returns the calculated value of Y.	x = False; y = True; X and Y, which returns false because X is false. Here, Python does not compute y because it knows that the value of the expression must be false (because X is false). This phenomenon is called short-circuit calculation.
Or	Boolean "or"	If x is true, it returns true, otherwise it returns the calculated value of Y.	x = True; y = False; X or Y returns true. Short-circuit calculations are also applicable here.