Python string manipulation (remove space strip (), slice, find, join join (), split split (), convert first letter uppercase, convert letter case ... ）

#可变变量: List, dictionary
#不可变变量: Meta-ancestor, string
Manipulation of strings (remove spaces, slices, find, join, split, convert first letter uppercase, convert letter case, determine if it is a numeric letter, member operator (In/not in))
strings are enclosed in single or double quotes: var1 = ' Hello '  var2 = ' World '

The string cannot modify the value, as shown in the following example:

The following are some of the common operations of strings.

1. Remove spaces
Str.strip ()  # Remove both spaces and line breaks
Str.strip (' a ') # Remove the characters specified on both sides
Str.lstrip () #去掉左边的空格
Str.rstrip () #去掉右边的空格



2. Find
Access string, you can get the string by using square brackets to find an index, s[0] # 1th
To truncate a string, S[2:-1] # 2nd to last
Find out if a character is present, S.find (' B ') # finds the index that returns B, returns the first one, and cannot find the return-1
Find out if there is a character, another way to use Index (), S.index (' B ') to find the index of return B, more than the first one, the error is not found
Find the number of characters, S.count (' a ')

3. Connect (with join () to concatenate list, tuple,dict to string)

4. Segmentation(spilt () splits the string into list)

5. Convert letter case (capitalized), all uppercase letters, all letters lowercase, print a string with style, ... To begin with; End, string substitution

Str.capitalize () #首字母大写

Str.upper () # turn all the letters into uppercase

Str.lower () # turn all the letters into lowercase

Str.center ((), '-') #字符串放中间, both sides-padded

Sql.startswith (' select ') # starts with select

File_name.endswith ('. xls ') # ends with. xls

Sql.replace (' Select ', ' Update ') #字符串替换, old--new

6. String Formatting (F.format (), F.format_map ())

7. Determine if it is a number, letter, space, \ t, \ n, \ r

8. In/not in (Member operator)

In: Member operator-returns TRUE if the string contains the given character

Not in: Member operator-returns TRUE if the string does not contain the given character

#in/not in
If I in D:
    Pass
If I not in D:
    Pass
Print (' A ' in ' ACDA ')  #-Ture
Print (' A ' not in ' AFDSHJW ') #-False

Python string manipulation (remove space strip (), slice, find, join join (), split split (), convert first letter uppercase, convert letter case ... ）