Python's three-mesh operator and the not-in operator use the example _python

The three-mesh operator is the ternary operator

The ternary expressions of some languages (such as Java) are as follows:

A result when a condition is true: the result of a false decision

Result=x if X

Python's ternary expression has the following several ways of writing:

if __name__ = = ' __main__ ':
	a = '
	b = ' True '
	c = ' False '
	
	#方法一: Results of true if the result if the condition else is false
	D = B if a El Se c
	Print (' Method one output: ' + d ')
	
	#方法二: The result of the condition and true when the result or is false
	d = A and B or C
	print (' method Two output result: ' + d ')
	
	#以上 Both methods are equivalent to if ... else ...
	If a:
		d = b
	else:
		d = C
	print (the output of the ' if statement: ' + d ')

Output results:

Description
Judgment condition: A is an empty string, so the judgment condition is false
The result of the judgment when the condition is true: D = b
The result when the condition is false: D = C

x = [x for x-in range (1,10)]
print (x)
y =[] result

= True if it isn't in x else False # This is the best way
   
    print (Result) Result
= True if not of x else False # This way just like as ' (not in X '
print (Result)

Print (x is y)
print (x isn't y) # this is ' Best way
print (not X was Y) # this way just like as ' (not x) is Y " , so upper are the best way result

= 2 if 1 < 2 else 5 if 4 > 5 Else 6 # just as 1 > 2? 2:4 > 5? 5:6< C11/>print (Result)

   

Not specific use and meaning in Python

Name= ' While not
name:
 name=raw_input (U ' Please enter name: ')
print name

What does not in Python specifically represent:

In Python, not is a logical word, used for Boolean true and False,not true to false,not false to True, and the following are several common uses of not:
(1) Not and the logical judgment sentence if used to execute the statement after the colon, when the expression after not is false. Like what:

A = False
if not a: (here because A is False, not A is true)
 print "Hello"

Here we can output the results hello
(2) to determine whether an element is in a list or a dictionary, if a isn't in B,a is an element, B is a list or a dictionary, meaning that if a is not in list B, then execute the statement following the colon, such as:

A = 5
b = [1, 2, 3]
if a not in B:
 print "Hello"

We can also output the results here Hello

Not x means equivalent to if X is false, then True, else false

There are three main ways in which a variable is always judged to be none:

The first is "if X is None";
The second type is ' if not x: ';
The third is ' if not ' (this is a clearer understanding of ' if not ' (x is None) ').

If you think it makes no difference, then you should be careful, there is a hole in it. Let's take a look at the code:

>>> x = 1
>>> not x
false
>>> x = [1]
>>> not x
False
>& gt;> x = 0
>>> not x
True
>>> x = [0]   # you don ' t want to fall
in this one. >>> not x
False

For more information, refer to this article: http://www.jb51.net/article/93165.htm