python之字符串函数

1. endswith() startswith()

1 # 以什么什么结尾
2 # 以什么什么开始
3 test = "alex"
4 v = test.endswith('ex')
5 v = test.startswith('ex')
6 print(v)

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2. expandtabs()

1 test = "1	2345678	9"
2 v = test.expandtabs(6)
3 print(v,len(v))

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3. find()

1 # 从开始往后找，找到第一个之后，获取其未知
2 # > 或 >=
3 test = "alexalex"
4 # 未找到 -1
5 v = test.find('e')
6 print(v)

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4. index()

1 # index找不到，报错   忽略
2 test = "alexalex"
3 v = test.index('a')
4 print(v)

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5. format() format_map()

 1 # 格式化，将一个字符串中的占位符替换为指定的值
 2 test = 'i am {name}, age {a}'
 3 print(test)
 4 v = test.format(name='alex',a=19)
 5 print(v)
 6 
 7 test = 'i am {0}, age {1}'
 8 print(test)
 9 v = test.format('alex',19)
10 print(v)
11 
12 # 格式化，传入的值 {"name": 'alex', "a": 19}
13 test = 'i am {name}, age {a}'
14 v1 = test.format(name='df',a=10)
15 print(v1)
16 v2 = test.format_map({"name": 'alex', "a": 19})
17 print(v2)

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6. isalnum()

1 # 字符串中是否只包含 字母和数字
2 test = "er;"
3 v = test.isalnum()
4 print(v)

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7.capitalize() 首字母大写

1 test = "sqy"
2 v = test.capitalize()
3 print(v)

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8. casefold() lower() 所有变小写，casefold更牛逼，很多未知的对相应变小写

1 test = "sqy"
2 v1 = test.casefold()
3 print(v1)
4 v2 = test.lower()
5 print(v2)

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9. center() 置宽度，并将内容居中

1 # 20 代指总长度
2 # *  空白未知填充，一个字符，可有可无
3 test = "sqy"
4 v = test.center(20,"中")
5 print(v)

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10. ljust() rjust() zfill()

 1 # test = "alex"
 2 # v = test.ljust(20,"*")
 3 # print(v)
 4 
 5 # test = "alex"
 6 # v = test.rjust(20,"*")
 7 # print(v)
 8 
 9 # test = "alex"
10 # v = test.zfill(20)
11 # print(v)

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11. count() 去字符串中寻找，寻找子序列的出现次数

1 test = "aLexalexr"
2 v = test.count('ex')
3 print(v)
4 
5 test = "aLexalexr"
6 v = test.count('ex',5,6)
7 print(v)

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12. isalpha() 是否是字母，汉子

1 test = "as大多数df"
2 v = test.isalpha()
3 print(v)

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13. isdecimal() isdigit() isnumeric() 当前输入是否是数字

1 test = "②" # 1，②,儿
2 v1 = test.isdecimal()
3 v2 = test.isdigit()
4 v3 = test.isnumeric()
5 print(v1,v2,v3)

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14.isprintable() 是否存在不可显示的字符

1 # 	   制表符
2 # 
   换行
3 test = "gdds	fdsfd"
4 v = test.isprintable()
5 print(v)

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15. isspace() 判断是否全部是空格

1 test = "  ass"
2 v = test.isspace()
3 print(v)

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16. istitle() title() 判断是否是标题

1 test = "Return True if all cased characters in S are uppercase and there is"
2 v1 = test.istitle()
3 print(v1)
4 v2 = test.title()
5 print(v2)
6 v3 = v2.istitle()
7 print(v3)

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17. join() 将字符串中的每一个元素按照指定分隔符进行拼接

1 test = "你是风儿我是沙"
2 print(test)
3 t = ' '
4 v = "_".join(test)
5 print(v)

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18. islower() lower() isupper() upper()

1 test = "Alex"
2 v1 = test.islower()
3 v2 = test.lower()
4 print(v1, v2)
5 
6 v1 = test.isupper()
7 v2 = test.upper()
8 print(v1,v2)

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19. lstrip() rstrip() strip() 移除指定字符串有限最多匹配

 1 test = "
xas12xa
	xax1221axa  "
 2 v = test.lstrip('xa')
 3 v = test.rstrip('9lexxexa')
 4 v = test.strip('xa')
 5 print(v)
 6 
 7 test.lstrip()
 8 test.rstrip()
 9 test.strip()
10 # 去除左右空白
11 v = test.lstrip()
12 v = test.rstrip()
13 v = test.strip()
14 print(v)
15 print(test)
16 # 去除	 

17 v = test.lstrip()
18 v = test.rstrip()
19 v = test.strip()
20 print(v)

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20. maketrans() translate() 对应关系替换

1 v = "asidufkasd;fiuadkf;adfkjalsdjf"
2 m = str.maketrans("aeiou", "12345")
3 new_v = v.translate(m)
4 print(new_v)

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21. partition() rpartition() 分割为三部分

1 test = "testasdsddfg"
2 v = test.partition('s')
3 print(v)
4 v = test.rpartition('s')
5 print(v)

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22. split() rsplit() splitlines()

 1 test = "sqys"
 2 v = test.split('s',2)
 3 print(v)
 4 v = test.rsplit()
 5 print(v)
 6 
 7 
 8 # 23 分割，只能根据，true，false：是否保留换行
 9 # test = "asdfadfasdf
asdfasdf
adfasdf"
10 # v = test.splitlines(False)
11 # print(v)

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23. swapcase() 大小写转换

1 test = "aLex"
2 v = test.swapcase()
3 print(v)

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24. isidentifier() 字母，数字，下划线：标识符 def class

1 a = "de12_f"
2 v = a.isidentifier()
3 print(v)

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25.replace() 将指定字符串替换为指定字符串

1 test = "alexalexalex"
2 v = test.replace("ex",'bbb')
3 print(v)
4 v = test.replace("ex",'bbb',2)
5 print(v)

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26.灰魔法

　　一、for循环　　　

 1 test = "返回到合肥东方红刚才修改"
 2 # for 变量名 in 字符串:
 3 #     变量名
 4 # break
 5 # continue
 6 
 7 
 8 index = 0
 9 while index < len(test):
10     v = test[index]
11     print(v)
12 
13     index += 1
14 print('=======')
15 
16 for zjw in test:
17     print(zjw)
18 
19 test = "好方法个地方个地方刚发的"
20 for item in test:
21     print(item)
22     break
23 
24 for item in test:
25     continue
26     print(item)

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　　二、索引，下标，获取字符串中的某一个字符

1 test = "好方法个地方个地方刚发的"
2 v = test[3]
3 print(v)

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　　三、切片

1 test = "好方法个地方个地方刚发的"
2 v = test[0:10] # 0=<  <1
3 print(v)

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　　四、获取长度

1 # Python3： len获取当前字符串中由几个字符组成
2 test = "好方法个地方个地方刚发的"
3 v = len(test)
4 print(v)

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27. range()　　获取连续或不连续的数字

 1 # Python2中直接创建在内容中
 2 # python3中只有for循环时，才一个一个创建
 3 v = range(10)
 4 v = range(3,10)
 5 v = range(1,10,2)
 6 # 帮助创建连续的数字,通过设置步长来指定不连续
 7 v = range(0, 100, 5)
 8 
 9 for item in v:
10     print(item)

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28.zip()

 1 # print(list(zip(('a','n','c'),(1,2,3))))
 2 # print(list(zip(('a','n','c'),(1,2,3,4))))
 3 # print(list(zip(('a','n','c','d'),(1,2,3))))
 4 #
 5 # p={'name':'alex','age':18,'gender':'none'}
 6 # print(list(zip(p.keys(),p.values())))
 7 # print(list(p.keys()))
 8 # print(list(p.values()))
 9 #
10 print(list(zip(['a','b','c'],'12345')))

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