Detailed explanation of how to use str string in python3

This article mainly introduces the tutorial on the use of str (string) in python3. The introduction in the article is very detailed. The operations of various str strings in python3 are included in this article. Friends who need it can refer to it. , let’s take a look below.

This article mainly introduces a summary of the use of str (string) in python3. The introduction in the article is very detailed. Friends who need it can take a look below.

__add__ function (appends a string at the end)

s1 ='Hello'
s2 = s1.__add__(' boy!')
print(s2)

#输出：Hello boy!

__contains__ (determines whether a string is contained, and returns True if it does)

s1 = 'Hello'
result = s1.__contains__('He')
print(result)

#输出：True

__eq__ (determines two characters Whether the strings are the same, return True if they are the same)

s1 = 'Hello'
s2 = 'How'
result = s1.__eq__(s2)
print(result)

#输出：False

__format__

#占位

__getattribute__

#占位

__getitem__

#占位

__getnewargs__

#占位

__ge__ ( Greater than or equal to)

print('b'.__ge__('a'))

#输出：True

__gt__(greater than)

print('b'.__ge__('a'))

#输出：True

__hash__

#占位

__iter__

#占位

__len__(return string length)

print('abc'.__len__())

#输出：3

__le__ (less than or equal to)

print('b'.__le__('a'))

#输出：False

__lt__ (less than)

print('b'.__lt__('a'))

#输出：False

__mod__

#占位

__mul__

#占位

__new__

#占位

__ne__

#占位

__repr__

#占位

__rmod__

#占位

__rmul__

#占位

__sizeof__

#占位

__str__(return to self)

print('abc'.__str__())

#输出：abc

capitalize (capitalize the first letter)

s = 'tom'
print(s.capitalize())

#输出：Tom

casefold (convert uppercase to lowercase)

s = 'TOM'
print(s.casefold())

#输出：tom

center (specify the length and padding characters, the content is centered, and the padding characters are left blank if they are spaces)

s = 'Tom'
print(s.center(20,'-'))

#输出：--------Tom---------

count (calculate the number of occurrences of a certain string, the second parameter: starting position, the third parameter: ending position)

s = 'aabbbcccccdd'
print(s.count('cc',3,11))

#输出：2

encode (encoding)

s = "中文"
print(s.encode('gbk'))

#输出：b'\xd6\xd0\xce\xc4'

endswith (to determine whether a string ends with a certain character or string, the second parameter: starting position, the third parameter: ending position)

s = 'Projects'
print(s.endswith('ts'))
print(s.endswith('e',0,5))

#输出：True
# True

expandtabs (convert 1 tab key into 7 spaces)

s = 'H\ti'
print(s.expandtabs())

#输出：H i

find (find the index position of a character or string, second parameter: starting position, third parameter: ending position)

s = 'Hello'
print(s.find('o'))
print(s.find('o',0,3)) #找不到返回-1

#输出：4
# -1

format (String formatting/splicing)

name = 'Tom'
age = 18
s = '{0}\'s age is {1}'.format(name,age)
print(s)

#或者

str = '{name}\'s age is {age}'
result = str.format(age=18,name='Tom')
print(result)

#输出：Tom's age is 18

format_map

#占位

index (find the index position of a character or string, which is different from find. If the character does not exist, an error will be reported)

s = 'Hello'
print(s.index('o'))
print(s.index('e',0,3))

#输出：4
# 1

isalnum(whether it is a letter or number)

s = '!#'
print(s.isalnum())

#输出：False

isalpha(whether it is a letter)

s = '123'
print(s.isalpha())

#输出：False

isdecimal(whether it is a decimal number)

s = '123'
print(s.isdecimal())

#输出：True

#True: Unicode数字，，全角数字（双字节）
#False: 罗马数字，汉字数字
#Error: byte数字（单字节）

isdigit (whether it is a number)

s = '123'
print(s.isdigit())

#输出：True

#True: Unicode数字，byte数字（单字节），全角数字（双字节），罗马数字
#False: 汉字数字

isidentifier (whether it is an identifier/variable name)

s = '1num'
print(s.isidentifier())

#输出：False
#因为变量名不能以数字开头

islower (whether it is all lowercase letters)

s = 'Hello'
print(s.islower())

#输出：False

isnumeric (whether it is a number)

s = '123'
print(s.isnumeric())

#输出：True

#True: Unicode数字，全角数字（双字节），罗马数字，汉字数字

isprintable (whether it is a printable character/can it be output as is)

s = '\n'
print(s.isprintable())

#输出：False

isspace (whether it is a space)

print(' '.isspace())
print('\t'.isspace())

#输出：True
# True

istitle (whether it is a title/the beginning of each word Letters in uppercase)

print('Hello Boy'.istitle())
print('hello boy'.istitle())

#输出：True
# False

isupper (whether all letters are in uppercase)

print('BOY'.isupper())
print('Boy'.isupper())

#输出：True
# False

join (join the elements in the sequence with specified characters to generate a new string)

s = ['H','e','l','l','o']
print(''.join(s))
print('-'.join(s))

#输出：Hello
# H-e-l-l-o

ljust (Specify the length and padding characters, the content is left-justified, and the padding characters are left blank if they are spaces)

s = 'Hello'
print(s.ljust(10,'-'))

#输出：Hello-----

lower (all strings are changed to lowercase)

s = 'TOM'
print(s.lower())

#输出：tom

lstrip (remove the string The characters specified on the left, the default is a space)

s = ' Tom'
print(s.lstrip())

#输出：Tom

maketrans (Create a conversion table for character mapping, used with the translate function)

intab = "abcde"
outtab = "12345"
trantab = str.maketrans(intab, outtab)

str = "Hello abc"
print (str.translate(trantab))

#输出：H5llo 123

partition (Specify the separator to split the string)

s = 'IamTom'
print(s.partition('am'))

#输出：('I', 'am', 'Tom')

replace (Replace old (old string) in the string with new (new string). If the third parameter max is specified, the replacement will not exceed max times. )

s = 'Tom'
print(s.replace('m','o'))

#输出：Too

rfind(Find the position where the specified string appears from the right, if there is no match, return -1)

s = 'one two one'
print(s.rfind('one'))
print(s.rfind('one',0,6)) #指定起始和结束位置

#输出：8
#  0

rindex(Find the position where the specified string appears from the right, if there is no match If there is a match, an error will be reported)

s = 'one two one'
print(s.rindex('one'))
print(s.rindex('one',0,6)) #指定起始和结束位置

#输出：8
#  0

rjust(Specify the length and padding characters, the content will be right-aligned, and the padding characters will be blank if left blank)

s = 'Hello'
print(s.rjust(10,'-'))

#输出：-----Hello

rpartition（ 指定分隔符，从右边开始将字符串进行分割）

s = 'IamTom_IamTom'
print(s.rpartition('am'))

#输出：('IamTom_I', 'am', 'Tom')

rsplit(指定分隔符对字符串进行切片，如果指定第二个参数num，则只分隔num次，最后返回一个列表)

s = 'a b c d'
print(s.rsplit())
print(s.rsplit(' ',2)) #从右边开始，按空格分隔两次

#输出：['a', 'b', 'c', 'd']
#  ['a b', 'c', 'd']

rstrip(删除字符串末尾的指定字符，默认为空格)

s = '!!! I am Tom !!!'
print(s.rstrip('!'))

#输出：!!! I am Tom

split(指定分隔符对字符串进行切片，如果指定第二个参数num，则只分隔num次，最后返回一个列表)

s = 'a b c d'
print(s.split())
print(s.split(' ',2)) #从左边开始，按空格分隔两次

#输出：['a', 'b', 'c', 'd']
# ['a', 'b', 'c d']

splitlines(按换行符来分隔字符串，返回一个列表)

s = 'a\nb\nc'
print(s.splitlines()) #默认参数为False
print(s.splitlines(True)) #指定Ture参数，则保留换行符

#输出：['a', 'b', 'c']
#  ['a\n', 'b\n', 'c']

startswith（判断字符串是否以某个字符或字符串开头的，第二个参数：起始位置，第三个参数：结束位置）

s = 'Projects'
print(s.startswith('Pr'))
print(s.startswith('e',4,8))

#输出：True
#  True

strip(删除字符串前后的指定字符，默认为空格)

s = '!!! I am Tom !!!'
print(s.strip('!'))

#输出： I am Tom

swapcase（大小写互换）

s = 'I am Tom'
print(s.swapcase())

#输出：i AM tOM

title(转换成标题，就是每个单词首字母大写)

s = 'i am tom'
print(s.title())

#输出：I Am Tom

translate（根据maketrans方法创建的表，进行字符替换）

intab = "abcde"
outtab = "12345"
trantab = str.maketrans(intab, outtab)

str = "Hello abc"
print (str.translate(trantab))

#输出：H5llo 123

upper(小写转换成大写)

s = 'Hello'
print(s.upper())

#输出：HELLO

zfill(指定字符串的长度。原字符串右对齐，前面填充0)

s = 'Hello'
print(s.zfill(10))

# 输出：00000Hello

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