Python old boy Day10

1. Operators
The result is a value
Arithmetic operations
A = 10 * 10
Assignment operations
A = a + 1 a+=1

The result is a Boolean value
Comparison operation
A = 1 > 5
Logical operations
A = 1>6 or 1==1
Member operations
A = "mosquito" in "Zheng Jianwen"

2. Basic data type

Python2 Int and long

only int in Python3.

numeric int, all functions, all in int
A1 = 123
A1 = 456

-INT
Convert a string to a number
A = "123"
Print (Type (a), a)

b = Int (a)
Print (type (b), B)

num = "0011"
v = int (num, base=2) equals num as a binary output in decimal
Print (v)

-Bit_lenght
Binary of the current number, represented by at least n bits
R = Age.bit_length ()

Age = 5
# 1 1
# 2 10
# 3 11
# 4 100
# 5 101

Print (R)

#首字母大写

Test = "ALex"
v = test.capitalize ()
Print (v)

#所有变小写, Casefold, a lot of unknown to the corresponding change lowercase
V1 = Test.casefold ()
Print (v1)
V2 = Test.lower ()
Print (v2)

#设置宽度, and center the content
Total length of 20-generation finger
Blank unknown padding, one character, optional
v = test.center (20, "medium")
Print (v)

#去字符串中寻找 to find the number of occurrences of a subsequence
Test = "ALEXALEXR"
v = test.count (' ex ')
Print (v)

Test = "ALEXALEXR"
v = test.count (' ex ', 5,6)

5,6 represents the start and end coordinates of a string
Print (v)

# What's the end of what?
# Start with what?
Test = "Alex"
v = test.endswith (' ex ')
v = test.startswith (' ex ')
Print (v)

#从开始往后找, after finding the first one, get its position
> or >=
Test = "Alexalex"
# Not found-1
v = test.find (' ex ')
Print (v)

# Index not found, error ignored
Test = "Alexalex"
v = test.index (' 8 ')
Print (v)

# formatting, replacing placeholders in a string with the specified values
Test = ' I am {name} ', age {A} '
Print (test)
v = test.format (name= ' Alex ', a=19)
Print (v)

Test = ' I am {0}, age {1} '
Print (test)
v = Test.format (' Alex ', 19)
Print (v)

# formatted, incoming value {"Name": ' Alex ', ' a ': 19}
Test = ' I am {name} ', age {A} '
V1 = Test.format (name= ' DF ', a=10)
V2 = Test.format_map ({"Name": ' Alex ', "a": 19})

The last two sentences have the same effect.

# whether the string contains only letters and numbers
Test = "123"
v = test.isalnum ()
Print (v)

Python old boy Day10