python常见的字符串处理函数

name = "my \tname is {name} and i am {year} old"#字符串的一个字母大写print(name.capitalize())运行结果：My name is {name} and i am {year} old

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name = "my \tname is {name} and i am {year} old"#获得字符串某一字符串的数目print(name.count("a"))运行结果：5

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name = "my \tname is {name} and i am {year} old"#总打印50字符，name居中，其余用"-"补齐print(name.center(50,"-"))运行结果：------my name is {name} and i am {year} old------

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name = "my \tname is {name} and i am {year} old"#判断字符串以什么结尾print(name.endswith("ex"))运行结果：False

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name = "my \tname is {name} and i am {year} old"#自定义tab与空格的关系print(name.expandtabs(tabsize=30))运行结果：my                            name is {name} and i am {year} old

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name = "my \tname is {name} and i am {year} old"#字符串切片，从name的位置开始print(name[name.find("name"):])运行结果：name is {name} and i am {year} old

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name = "my \tname is {name} and i am {year} old"#格式化字符串print(name.format(name='alex',year=23))print(name.format_map( {'name':'alex','year':12} ))运行结果：my name is alex and i am 23 oldmy name is alex and i am 12 old

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#阿拉伯字符和阿拉伯数字（字母和数字）print('ab23'.isalnum())运行结果：True

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#判断字符串是否由英文字母组成print('abA'.isalpha())运行结果：True

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#是否是十进制print('1A'.isdecimal())运行结果：False

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#检查字符串是否仅包含数字print('1A'.isdigit())运行结果：False

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#判读是不是一个合法的标识符（是不是合法的变量名）print('a 1A'.isidentifier())运行结果：False

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#是否标题（单词首字母大写）print('My Name Is '.istitle())运行结果：True

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#tty file ,drive file等不可打印print('My Name Is '.isprintable())运行结果：True

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#字符串是否全是大写print('My Name Is '.isupper())运行结果：False

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#连接字符串print('+'.join( ['1','2','3']) )运行结果：1+2+3

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#右补齐print( name.ljust(50,'*') )运行结果：my name is {name} and i am {year} old************

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#左补齐print( name.rjust(50,'-') )运行结果：------------my name is {name} and i am {year} old

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print( 'Alex'.lower() )运行结果：alex

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print( 'Alex'.upper() )运行结果：ALEX

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print( '\nAlex'.lstrip() )运行结果：Alex

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print( 'Alex\n'.rstrip() )运行结果：Alex

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print( ' sunchengqaun\n'.strip() )运行结果：sunchengquan

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p = str.maketrans("abcdefli",'123$@456')print("alex li".translate(p) )运行结果：15@x 56

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print('alex li'.replace('l','L',1))运行结果：aLex li

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#split([sep [,maxsplit]])#sep 可选参数 ，指定分割的字符，默认为空格#maxsplit 可选参数 ， 分割次数print('1+2+3+4'.split('\n'))运行结果：['1+2+3+4']

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print('1+2\n+3+4'.splitlines())运行结果：['1+2', '+3+4']

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#大写变小写，小写变大写print('Alex Li'.swapcase())运行结果：aLEX lI

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print('lex li'.title())运行结果：Lex Li

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print('lex li'.zfill(50))运行结果：00000000000000000000000000000000000000000000lex li