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chapter3 使用字符串

chapter3 使用字符串

作者: Andrew12 | 来源:发表于2018-08-05 21:34 被阅读0次

    concepts and notations

    concepts

    1. 字符串不可变;

    notations

    %s 转换说明符,将指定值转换为字符串类型
    %.3f 带有3位小数的浮点数

    设置字符串格式

    method1:格式设置运算符%

    • 针对单个值(string or number)
    • 针对多个值(tuple)
    >>> format = "Hello, %s. %s enought for ya?"
    >>> values = ('world', 'Hot')
    >>> format % values
    

    method2:字符串方法format

    # 待替换字段-无名称
    >>> "{}, {} and {}".format("first", "second", "third")
    'first, second, third'
    
    # 待替换字段-以索引为名称
    >>> "{0}, {1} and {2}".format("first", "second", "third")
    'first, second and third'
    >>> "{3}, {0}, {2}, {1}, {3}, {0}".format("be", "not", "or", "to")
    'to be or not to be'
    
    # 替换多个字段,参数顺序无关紧要
    # 指定格式说明符.2f(带有2位小数的浮点数),用冒号将格式说明符与字段名隔开
    >>> from math import pi
    >>> "{name} is approximately {value: .2f}.".format(value = pi, name = "pi")
    
    # 变量与待替换字段同名,可使用f字符串(f"")
    >>> from math import e
    >>> f"Eluer's constant is roughly {e}"
    >>> "Eluer's constant is rougtly 2.718281828459045"
    

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