小插曲之变量和字符串
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变量:
其他程序语言是给变量赋值,Python是把名字贴在值上;(只有名字,没有变量)
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程序测试:
>>> teacher = '小甲鱼' >>> print(teacher) 小甲鱼 >>> teacher = '老甲鱼' >>> print(teacher) 老甲鱼 >>> first = 3 >>> second = 8 >>> third = first + second >>> print(third) 11 >>> myteacher = '小甲鱼' >>> yourteacher = '黑夜' >>> ourteacher = myteacher + yourteacher >>> ourteacher '小甲鱼黑夜' >>> print(ourteacher) 小甲鱼黑夜 >>> myteacher '小甲鱼'
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变量的命名规则和C语言相似;
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字符串
>>> 5+8 13 >>> '5'+'8' '58'
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单双引号
既可以单引号,又可以是双引号,但必须成对;
>>> 'i love you" File "<stdin>", line 1 'i love you" ^ SyntaxError: EOL while scanning string literal
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转义字符
>>> 'let's go' File "<stdin>", line 1 'let's go' >>> 'let\'s go' "let's go"
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原始字符串
>>> str = 'C:\now' >>> str 'C:\now' >>> print(str) #优先识别\n C: ow >>> str = 'C:\\now' #用\的转义字符 >>> print(str) C:\now >>> str=r'C:\now' #r表示原始字符,不进行转义 >>> print(str) C:\now >>> str 'C:\\now' #实际上是自动进行转义,但结尾不能是\
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长字符串
三重引号字符串,多行的字符串
>>> str = '''我 ... 爱 ... 你''' >>> print(str) 我 爱 你