今天就介紹一下常用的字符串操作,都是以 Python3
撰寫的
首字母變大寫
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
name = "ironman"
print(name.capitalize())
---------------執行結果---------------
Ironman
計算字符串重複的字共出現幾次
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
name = "i am a ironman"
print(name.count('a'))
---------------執行結果---------------
3
把字符串置中後,長度要50
,不足50的就用-
補滿
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
name = "i am a ironman"
print(name.center(50, "-"))
---------------執行結果---------------
------------------i am a ironman------------------
以xx
為結尾的,就返回True,不是就False
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
name = "i am a ironman"
print(name.endswith("an"))
print(name.endswith("i"))
---------------執行結果---------------
True
False
會把字符串中的\t
變成20個空白格,default tabsize=8
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
name = "i \tam a ironman"
print(name.expandtabs(tabsize=20))
---------------執行結果---------------
i am a ironman
算字符串長度
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
name = "i am a ironman"
print(len(name))
---------------執行結果---------------
14
可以透過find()
找出字符串要切片的起始位置,沒找到返回-1
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
name = "i am a ironman"
>>> print(name.find("am"))
2 # 找到切片起始位置是2
>>> print(name[name.find("am"):3])
a
>>> print(name[name.find("am"):4])
am
>>> print(name[name.find("am"):5])
am
>>> print(name[name.find("am"):6])
am a
>>> print(name[name.find("am"):7])
am a
>>> print(name[name.find("am"):8])
am a i
>>> print(name[name.find("am"):9])
am a ir
>>> print(name[name.find("am"):10])
am a iro
>>> print(name[name.find("am"):])
am a ironman
透過formate()
對字符串做格式化
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
name = "My name is {name} and I'm {years} old"
>>> print(name.format(name='ironman', years='18'))
My name is ironman and I'm 18 old
使用format_map()
對字符串做格式化, 替換字段使用{} 大括號
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
name = "My name is {name} and I'm {years} old"
>>> print(name.format_map( {'name':'ironman', 'years':'18' } )) # {} 是一種字典的形式
My name is ironman and I'm 18 old
查找name
這個字符串的下標位置
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
name = "i am a ironman"
>>> print(name.index(name))
0
判斷字符串裡,是不是由數字或是大小寫英文字母組成的,為真就返回True
,若是有包含特殊符號的為就會返回False
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print('123'.isalnum())
True
>>> print('abc'.isalnum())
True
>>> print('ABC'.isalnum())
True
>>> print('abc123'.isalnum())
True
>>> print('ABC123'.isalnum())
True
>>> print('abc123@'.isalnum())
False
>>> print('ABC123.'.isalnum())
False
判斷字符串,是不是所有字符都是為大小寫的英文字母,為真返回True
,反則返回False
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print('ABC'.isalpha())
True
>>> print('abc'.isalpha())
True
>>> print('abc123'.isalpha())
False
>>> print('abc@'.isalpha())
False
>>> print('abc1@'.isalpha())
False
判斷字符串中,是不是為十進制的數字
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print('11'.isdecimal())
True
>>> print("1234".isdecimal())
True
>>> print("12.34".isdecimal())
False
>>> print("1A".isdecimal())
False
判斷字符串中,是不是數字(整數)
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print('1234'.isdigit())
True
>>> print('12.34'.isdigit())
False
判斷字符串中,是不是合法的標識符,也就是變量名
命名是否合法
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print('_Python3'.isidentifier())
True
>>> print('1_Python3'.isidentifier())
False
>>> print('__Python3'.isidentifier())
True
>>> print('{Python3}'.isidentifier())
False
>>> print('我好弱'.isidentifier()) # 一般不會用中文當變量名,請勿使用
True
判斷字符串中,是不是小寫字母,不管有沒有特殊符號,為真返回True
,為否返回False
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print('abc'.islower())
True
>>> print('abC'.islower())
False
>>> print('ab1'.islower())
True
>>> print('ab!@'.islower())
True
判斷字符串中,是不是數字,為真返回True
,為否返回False
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print('1234'.isnumeric())
True
>>> print('12.34'.isnumeric())
False
>>> print('12A'.isnumeric())
False
判斷字符串裡,是不是空格
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print(' '.isspace())
True
>>> print('\r\t\n '.isspace())
True
>>> print('\n '.isspace()) # 換行,游標在下一行
True
>>> print('\t '.isspace()) # tab鍵,8個空格
True
>>> print('\r '.isspace()) # 換行,游標在上一行
True
判斷字符串裡,每個字母第一個字為大寫,為真返回True
,為否返回False
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print('My Name Is'.istitle())
True
>>> print('My Name is'.istitle())
False
判斷字符串裡,是不是可以打印的字符串或是字符串為空,為真返回True
,為否返回False
,(不常用)
S.isprintable() -> bool
Return True if all characters in S are considered
printable inrepr() or S is empty
, False otherwise
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print('My Name Is'.isprintable())
True
>>> print('123.34'.isprintable())
True
>>> print(' '.isprintable())
True
>>> print('\n'.isprintable())
False
>>> print('\t'.isprintable())
False
判斷字符串裡,每個字母是不是大寫,為真返回True
,為否返回False
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print('MY NAME IS'.isupper())
True
>>> print('MY NAME iS'.isupper())
False
使用字符串作為分隔符,串連多個數據成一個字符串
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> s = ",".join(('Python', '3'))
>>> print(s)
Python,3
>>> print('+'.join(['1', '2', '3', '4']))
1+2+3+4
字符串內容往左對齊,並使用指定字符填充剩餘長度
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print(name.ljust(50, '*'))
i am a ironman************************************
字符串內容往右對齊,並使用指定字符填充剩餘長度
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print(name.rjust(50, '*'))
************************************i am a ironman
字符串轉換成小寫
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print('IRONMAN'.lower())
ironman
字符串轉換成大寫
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print('ironman'.upper())
IRONMAN
刪除字符串左邊空格和enter,或是指定中的字符
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> s = " i am ironman"
>>> print(s.lstrip())
i am ironman
>>> s = "i am ironman"
>>> print(s.lstrip('i am'))
ronman
刪除字符串右邊空格和enter,或是指定中的字符
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> s = "i am ironman "
>>> print(s.rstrip())
i am ironman
>>> s = "i am ironman"
>>> print(s.rstrip('man'))
i am iro
刪除字符串左右二邊空格和enter,或是指定中的字符
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print('\nironman\n'.strip())
ironman
>>> s = " i am a ironman "
>>> print(':', s.strip(), ':')
: i am a ironman :
>>> s = "i am a ironman"
>>> print(s.strip('man'))
i am a iro
轉換表,請注意觀察,才會了解有什麼差異
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> p = str.maketrans("abcdef", '123456')
>>> print("i am a ironman".translate(p))
i 1m 1 ironm1n
在字符串中,把old字符串取代成new的字符串
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print('ironman'.replace('i', 'I', 1))
Ironman
>>> print('ironman'.replace('r', 'R', 2))
iRonman
>>> print('i am a ironman'.replace('a', '.'))
i .m . ironm.n
在字符串中,從右邊開始找,找到最後一個的字符給打印出來下標位置
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> s = "i am a ironman"
>>> print(s.rfind("a"))
12
把字符串拆成列表
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print('1+2+3+4'.split('+'))
['1', '2', '3', '4']
>>> print('1+2\n+3+4'.split('\n'))
['1+2', '+3+4']
**字符串以換行符為分隔符拆分,去掉換行符;keepends為True,保留換行符
**
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print('1+2\n+3+4'.splitlines())
['1+2', '+3+4']
>>> print('1+2\n+3+4'.splitlines(keepends=True))
['1+2\n', '+3+4']
字符串裡把小寫字母變大寫,大寫字母變小寫
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print('Tony Stark'.swapcase())
tONY sTARK
字符串裡每個單字的第一個字母變成大寫,其餘字母都會被轉成小寫
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print('tony stark'.title())
Tony Stark
>>> print('hELLO wORLD pYTHON3'.title())
Hello World Python3
在字符串的左邊填0
#!/usr/bin/env python3
# -*- coding:utf-8 -*-
>>> print('tony stark'.zfill(10))
tony stark
>>> print('tony stark'.zfill(20))
0000000000tony stark
參考來源:
其實也不是常用的@@" 完全就是把內建的都試過一次…好累