How to manipulate Python strings

1. String length

#strlen (str) # string length function name
Str= ' Apples ' # assigns the string "apples" to the variable str
Print (len (str)) # Prints the length of the string

2. Find characters

#strchr (STR1,STR2) # Find character function names
str1 = ' apples '
str2 = ' E '
result = Str1.index (str2) # finds characters in string str1 str2
Print (Result)

3. Copying strings

#strcpy (STR1,STR2) # Copy String function name
str1 = ' apples '
STR2 = str1 # Assigns the string str1 to str2
str1 = ' Bananas ' # re-assigning string to STR1
Print (STR2)

4. Connection string

#strcat (STR1,STR2) # connection string function name
str1 = ' apples '
str2 = ' Bananas '
STR1 + = str2 # string str1 concatenation with string str2 and assign to STR1
Print (STR1)

5. Uppercase and lowercase conversions in strings

Str.lower () #小写
Str.upper () #大写
Str.swapcase () #大小写互换
Str.capitalize () #首字母大写

#strupr (str)
str = ' ABCDEFGH '
str = Str.upper ()
Print (str)

#strlwr (str)
str = ' ABCDEFGH '
str = Str.lower ()
Print (str)

6. Reverse the string

#strrev (str) # reverse String function name
str = ' ABCDEFG '
str = str[::-1] # index from start to end, third parameter-1 for reverse
Print (str)

7. Finding strings

#strstr (STR1,STR2) # Find string function names
str1 = ' ABCDEFG '
str2 = ' CDE '
Print (Str1.find (str2)) # Find string in string str1 str2

#变量. Find ("What to Look for", [start position, end position]), start position and end position, indicate the range to look for, and empty means find all. The location is returned after finding it, the position is calculated from 0, and 1 is returned if not found.

8. String substitution

str = ' ABCABCABC '
Str=str.replace (' A ', ' 0 ') # replaces the character "a" in the string str with "0" and re-assigns the value to STR
Print (str)

9. String alignment

Str.ljust (N,[fillchar]) # output n characters, Str left-aligned, insufficient portions are filled with Fillchar, the default is a space.
Str.rjust (N,[fillchar]) # ibid., Align Right
Str.center (n, [Fillchar]) # ibid., Center

10. Other functions

Str.count (char, [Start, [end]]) #计算字符char在字符串str中出现的次数, you can set where to start and where to end

Str.strip ([chars]) #把str中字符chars前后的字符全部去掉, can be understood to replace s before and after chars to none
Str.lstrip ([chars]) # Remove the left part of the character chars
Str.rstrip ([chars]) # Remove the right part of the character chars

Str.split ([Sep, [Maxsplit]]) #以sep为分隔符, divides str into a list,maxsplit that represents the number of splits, and the default delimiter is a blank character

Str.startswith (char) #是否以char开头
Str.endswith (char) #以char结尾
Str.isalnum () #str是否全是字母和数字
Str.isalpha () #str是否全是字母
Str.isdigit () #str是否全是数字
Str.isspace () #str是否全是空白字符
Str.islower () #str中的字母是否全是小写
Str.isupper () #str中的字母是否便是大写
Str.istitle () #str是否是首字母大写的

11. String slicing

str = ' abcdefghigklm′
Str[0:3] #截取第一位到第三位的字符 # "ABC"
Str[:] #截取字符串的全部字符 # "ABCDEFGHIGKLM" 　　　　　　　　　　　Br>str[6:] #截取第七个字符到结尾 # "HIGKLM"
Str[:-3] #截取从头开始到倒数第三个字符之前 # "Abcdefghig"
Str[2] #截取第三个字符 # "C"
Str[-1] #截取倒数第一个字符 # "M"
Str[::-1] #字符串倒序 # "MLK GIHGFEDCBA "
Str[-3:-1] #截取倒数第三位与倒数第一位之前的字符 #" KL "
Str[-3:] #截取倒数第三位到结尾 #" KLM "
Str [: -5:-3] #倒序截取后四位字符, and 2 characters to intercept # "MG"