Python3 str类型的方法

 

　capitalize()

　　将字符串第一个字母转换为大写，其他不变

def capitalize(self): # real signature unknown; restored from __doc__
    """
    S.capitalize() -> str
    
    Return a capitalized version of S, i.e. make the first character
    have upper case and the rest lower case.
    """
    return ""

　　

    例：

#!/usr/bin/env python
i = 'this is a test'
print( i.capitalize())

#输出结果：
This is a test

　

　casefold()
　　将字符串全部转换为小写，该方法与lower()方法的效果类似，但也有不同。

　　官方说明：https://docs.python.org/3/library/stdtypes.html#str.casefold

def casefold(self): # real signature unknown; restored from __doc__
    """
    S.casefold() -> str
    
    Return a version of S suitable for caseless comparisons.
    """
    return ""

　　

    例：

#!/usr/bin/env python
i = 'THIS IS A TEST'
print( i.casefold())
#输出结果：
this is a test

 

　center()
　　以给定为中心，输出一个宽度为width的字符串，并使用fillchar指定的字符填充，fillchar默认为空白

def center(self, width, fillchar=None): # real signature unknown; restored from __doc__
    """
    S.center(width[, fillchar]) -> str
    
    Return S centered in a string of length width. Padding is
    done using the specified fill character (default is a space)
    """
    return ""

　　

    例：

#!/usr/bin/env python
i = 'Test'
print(12345678901234567890)
print(i.center(20))
print(i.center(20,'*'))
#输出结果：
12345678901234567890
        Test        
********Test********

 

　count()

　　该方法返回给定字符在字符中出现的次数，并可以指定在字符串中统计次数的范围

    def count(self, sub, start=None, end=None): # real signature unknown; restored from __doc__
        """
        S.count(sub[, start[, end]]) -> int
        
        Return the number of non-overlapping occurrences of substring sub in
        string S[start:end].  Optional arguments start and end are
        interpreted as in slice notation.
        """

　　例：

#!/usr/bin/env python
i = 'this is a Test'
print(i.count('t'))
print(i.count('T'))
print(i.count('s'))
print(i.count('s',4,9))
print(i.count('s',4,))
#输出结果：
2
1	
3
1
2

　encode()

　　该方法