python字符串常用方法
1、isalnum():判斷字符串所有的字符都是字母或者數字。返回true和false
In [1]: str1=‘jiangwei520‘
In [2]: str2=‘jiang wei‘
In [3]: str3=‘520‘
In [4]: str4=‘520 1314‘
In [5]: str1.isalnum()
Out[5]: True
In [6]: str2.isalnum()
Out[6]: False
In [7]: str3.isalnum()
Out[7]: True
In [8]: str4.isalnum()
Out[8]: False
2、isalpha()
In [11]: s1=‘j w‘ In [12]: s2=‘jw‘ In [13]: s1.isalpha() Out[13]: False In [14]: s2.isalpha() Out[14]: True
3、isdigit():判斷字符串所有的字符都是數字。返回true和false
In [15]: n1=‘12 34‘ In [16]: n2=‘1234‘ In [17]: n3=‘1.1‘ In [18]: n1.isdigit() Out[18]: False In [19]: n2.isdigit() Out[19]: True In [20]: n3.isdigit() Out[20]: False
4、islower():判斷所有的字符都是小寫。
In [23]: s1=‘j w‘ In [24]: s2=‘jw‘ In [25]: s3=‘JW‘ In [26]: s1.islower() Out[26]: True In [27]: s2.islower() Out[27]: True In [28]: s3.islower() Out[28]: False
5、isupper():判斷所有的字符都是大寫。
In [29]: s1=‘J w‘ In [30]: s2="J W" In [31]: s3="JＷ" In [32]: s4=‘Jw‘ In [33]: s1.isupper() Out[33]: False In [34]: s2.isupper() Out[34]: True In [35]: s3.isupper() Out[35]: True In [36]: s4.isupper() Out[36]: False
6、istitle():判斷每個單詞的首字母都是大寫。
In [37]: s1=‘hello world‘ In [38]: s2=‘Hello World‘ In [39]: s3=‘Hello,world‘ In [40]: s4=‘HELLO WORLD‘ In [41]: s1.istitle() Out[41]: False In [42]: s2.istitle() Out[42]: True In [43]: s3.istitle() Out[43]: False In [44]: s4.istitle() Out[44]: False
7、lower()：轉小寫
In [47]: s4 Out[47]: ‘HELLO WORLD‘ In [48]: s4.lower() Out[48]: ‘hello world‘ In [49]: s2 Out[49]: ‘Hello World‘ In [50]: s2.lower() Out[50]: ‘hello world‘
7、upper()：轉大寫
In [54]: s1 Out[54]: ‘HEllo WOrld‘ In [55]: s3 Out[55]: ‘Hello,world‘ In [56]: s1.upper() Out[56]: ‘HELLO WORLD‘ In [57]: s3.upper() Out[57]: ‘HELLO,WORLD‘
8、strip([chars]):去除
lstrip()和rstrip()類似
In [61]: s1=‘ hello world !!! ‘ In [62]: s1.strip() Out[62]: ‘hello world !!!‘
In [63]: s2=‘**** jw---love---you ****‘
In [64]: s2.strip(‘*‘)
Out[64]: ‘ jw---love---you ‘
#應該是去除兩邊的
In [107]: a=‘***111***‘
In [108]: a.lstrip(‘*‘)
Out[108]: ‘111***‘
In [109]: a.rstrip(‘*‘)
Out[109]: ‘***111‘
In [110]: a.strip(‘*‘)
Out[110]: ‘111‘
9、replace(old ,new, [count]):替換
In [72]: a=‘小喵和小九‘ In [73]: a.replace(‘喵‘,‘喵喵‘).replace(‘九‘,‘九九‘) Out[73]: ‘小喵喵和小九九‘ In [74]: b=‘jiangwei is a good good good boy‘ In [75]: b.replace(‘good‘,‘nice‘) Out[75]: ‘jiangwei is a nice nice nice boy‘ In [76]: b.replace(‘good‘,‘nice‘,2) Out[76]: ‘jiangwei is a nice nice good boy‘ In [77]: b.replace(‘good‘,‘nice‘,1) Out[77]: ‘jiangwei is a nice good good boy‘
10、split():切割。返回列表。
In [92]: path1 Out[92]: ‘a/b/c/d‘ In [93]: path1.split(‘/‘) Out[93]: [‘a‘, ‘b‘, ‘c‘, ‘d‘] In [88]: path=‘/home/centos/python3.6‘ In [89]: path Out[89]: ‘/home/centos/python3.6‘ In [90]: path.split(‘/‘) Out[90]: [‘‘, ‘home‘, ‘centos‘, ‘python3.6‘]
11、startswith():以指定的字符串開頭。發貨true和false。
endswith():類似
In [94]: a=‘helloworld‘ In [95]: b=‘hello world‘ In [96]: a.startswith(‘hello‘) Out[96]: True In [97]: b.startswith(‘hello‘) Out[97]: True In [98]: b.startswith(‘he‘) Out[98]: True
12、format():格式化輸出
In [111]: print(‘{name}---->{age}‘.format(name=‘xjm‘,age=21)) xjm---->21 In [112]:
13、title():把每個字符串的首字母大寫
In [112]: s=‘hello world python ‘ In [113]: s.title() Out[113]: ‘Hello World Python ‘
#與capitalize不同。就第一個單詞的首字母大寫
In [128]: a=‘hello world python‘
In [129]: a.capitalize()
Out[129]: ‘Hello world python‘
14、join():插入
In [117]: a=‘.‘ In [118]: a.join(‘jwlove‘) Out[118]: ‘j.w.l.o.v.e‘
In [124]: a=‘/‘
In [125]: b=(‘user‘,‘local‘)
In [127]: a.join(b)
Out[127]: ‘user/local‘
15、center(width,char):擴充
In [137]: a=‘Linux‘ In [138]: a.center(25,‘*‘) Out[138]: ‘**********Linux**********‘
In [140]: a.center(25)
Out[140]: ‘ Linux ‘
#ljust和rjust類似
In [142]: a.ljust(10,‘-‘)
Out[142]: ‘Linux-----‘
In [143]: a.rjust(10,‘-‘)
Out[143]: ‘-----Linux‘
16、splitlines():根據\r \n \r\n 切割。返回列表
In [151]: a=‘如果\n沒有\r如果‘ In [154]: print(a) 如果 如果 In [157]: a.splitlines() Out[157]: [‘如果‘, ‘沒有‘, ‘如果‘]
17、format_map():格式化輸出
In [158]: a=‘hello world {course}‘ In [160]: course1=‘python‘ In [161]: course2=‘java‘ In [178]: a.format(course=course1) Out[178]: ‘hello world java‘ In [179]: a.format(course=course2) Out[179]: ‘hello world python‘ In [181]: a.format_map(vars()) Out[181]: ‘hello world python‘
python字符串常用方法