How IOS developers learn python programming 3-operator 2

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member operator

in And not in yes Python Unique operators （ It's all lowercase ）. Used to determine whether an object belongs to a collection , Very fast . Back to True perhaps False.

1. Judge a Whether in list1 In the list ： 

list1 = [1, 2, 3, 4, 5]
a = 1

for i in list1:
    if i == a:
        print("a stay list1 in ")
    else:
        print('a be not in list1 in ')

flag = False
for i in list1:
    if i == a:
        flag = True
        break
if flag:
    print("a yes list1 One of the elements of ")
else:
    print("a No list1 The elements of ")
    
    
#  If you use in Operator , There's no need for such trouble 
list1 = [1, 2, 3, 4, 5]
a = 1
if a in list1:
    print("a yes list1 One of the elements of ")
else:
    print("a No list1 The elements of ")list1 = [1, 2, 3, 4, 5]
a = 1

for i in list1:
    if i == a:
        print("a stay list1 in ")
    else:
        print('a be not in list1 in ')

flag = False
for i in list1:
    if i == a:
        flag = True
        break
if flag:
    print("a yes list1 One of the elements of ")
else:
    print("a No list1 The elements of ")
    
    
#  If you use in Operator , There's no need for such trouble 
list1 = [1, 2, 3, 4, 5]
a = 1
if a in list1:
    print("a yes list1 One of the elements of ")
else:
    print("a No list1 The elements of ")list1 = [1, 2, 3, 4, 5]
a = 1

for i in list1:
    if i == a:
        print("a stay list1 in ")
    else:
        print('a be not in list1 in ')

flag = False
for i in list1:
    if i == a:
        flag = True
        break
if flag:
    print("a yes list1 One of the elements of ")
else:
    print("a No list1 The elements of ")
    
    
#  If you use in Operator , There's no need for such trouble 
list1 = [1, 2, 3, 4, 5]
a = 1
if a in list1:
    print("a yes list1 One of the elements of ")
else:
    print("a No list1 The elements of ")
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Identity operator

Python Characteristic grammar （ It's all lowercase ）：

• is Used to judge whether the reference of two variables is the same object （ You can use id() Get objects ）.
• is not opposite .

️ Be careful ： is And comparison operators == The difference between ：

• == Used to determine whether the values of objects referenced by variables are equal .

>>> a = [1,2,3]
>>> b = [1,2,3]
>>> a is b
False
>>> a == b
True

>>> a = 2
>>> b = 2.0 #  It can be done by id() Check the memory address  
>>> a is b  
False
>>> a == b
True
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Ternary operator

python The representation of the trinary operator in ：

True_statements if expression else False_statements
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for example ：

a = 1
b = 2
if a+b>3:
    print(a+b)
else:
    print(b-a)

a+b if a+b>3 else b-a   #  Ternary operator 
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Operator priority

The following table lists all operators from the highest to the lowest priority . Operators with higher priority have priority in calculation or processing , The same level is calculated from left to right （ Except for assignment operators , It's in right to left order ）：