Python之str内置函数

约定不等于承诺〃 2022-06-02 03:54 232阅读 0赞

*    
    
 *  **str.capitalize()**

>   
> 字串首字母大写

a_str = "hello World"
    print("%s capitalized is %s" % (a_str, a_str.capitalize()))

*    
    
 *  **str.casefold()**

>   
> 与lower()类似，将字串转换为小写，可用于大小写不敏感字串匹配  
> 与lower()不同的是：lower方法只对ASCII编码，对于其他语言（非汉语或英文）可以使用casefold()进行大小写转换。  
> ‘ß’是德语字符，其小写为’ss’

b_str = 'ß'
    print("%s casefolded is %s" % (b_str, b_str.casefold()))
    print("%s lower is %s" % (b_str, b_str.lower()))

\-**str.center(width\[, fillchar\])**

> 返回指定宽度width，以当前字串居中的字串，左右不足部分以fillchar来填充, 如果width不大于原字串宽度，则返回原字串

if len(c_str) % 2 == 0 :
         if len(c_str) + 1 == width:
             do padding one fillchar on the left
     else:
         if len(c_str) + 1 == width:
             do padding one fillchar on the right

c_str = 'abc'
    print(c_str.center(4, '#'))
    print(c_str.center(5, '#'))
    c_str = 'icbc'
    print(c_str.center(5, '#'))
    print(c_str.center(6, '#'))

*    
    
 *  **str.count(sub\[, start\[, end\]\])**

> 返回子串出现频率

sub1 = "a"
    sub2 = "ac"
    sub3 = "a"
    sub4 = "aa"
    d_str = "abcdndiacac"
    e_str = "aaaaa"
    print(d_str.count(sub1)) print(d_str.count(sub2)) print(e_str.count(sub3)) print(e_str.count(sub4))

*    
    
 *  **ljust(width\[, fillchar\])**

> 使用指定字符填充，使字符串左对齐

c_str = "icbc"
    # output: icbc$$
    print(c_str.ljust(6, '$'))

*    
    
 *  **rindex(sub\[, start\[, end\]\])**

> 使用指定字符填充，使字符串右对齐

c_str = "icbc"
    # output: $$icbc
    print(c_str.rjust(6, '$'))

\-**zfill(width)**

> 字符串右对齐，前面填充0，如果width小于原有子串长度，则返回原有子串

n_str = '98'
    print(n_str.zfill(5))
    n_str = '-98'
    print(n_str.zfill(5))
    n_str = '--98'
    print(n_str.zfill(5))
    n_str = '-98'
    print(n_str.zfill(2))
    # output:
    # 00098
    # -0098
    # -0-98
    # -98

[https://docs.python.org/3/library/stdtypes.html?\#str][https_docs.python.org_3_library_stdtypes.html_str]

[https_docs.python.org_3_library_stdtypes.html_str]: https://docs.python.org/3/library/stdtypes.html?#str