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  • 《Python核心编程》P21输入数值字符串→转整型


     

    >>> num=input()
    1234
    >>> num
    '1234'
    >>> num=input(haha:)
    SyntaxError: invalid syntax
    >>> num=input('haha:')
    haha:23
    >>> num
    '23'
    >>> print(num)
    23
    '
    >>> print(num)
    23
    >>> print('123:sdf',num)
    123:sdf 23
    >>> print('123:sdf:',num)
    123:sdf: 23
    >>> print('123:sdf: ',num)
    123:sdf:  23
    >>> print('zhuanzhengxing',int(num))
    zhuanzhengxing 23
    >>> print(int(num))
    23
    >>> print(int(num)*2)
    46
    >>> print('zhuanzhengxing',int(num)*2)
    zhuanzhengxing 46
    >>> print('zhuanzhengxing%d',int(num)*2)
    zhuanzhengxing%d 46
    >>> print('%d',int(num)*2)
    %d 46
    >>> print(%d,int(num)*2)
    SyntaxError: invalid syntax
    >>> print(%d%int(num)*2)
    SyntaxError: invalid syntax
    >>> print('%d'%int(num)*2)
    2323
    >>> # #前有%d,后用的逗号,没用%:%d当做字符输出了
    >>> print(%int(num)*2)
    SyntaxError: invalid syntax
    >>> print('zhuanzhengxing%d'%int(num)*2)
    zhuanzhengxing23zhuanzhengxing23
    >>>  print('zhuanzhengxing'%int(num)*2)
     
    SyntaxError: unexpected indent
    >>> print('zhuanzhengxing'%int(num)*2)
    Traceback (most recent call last):
      File "<pyshell#31>", line 1, in <module>
        print('zhuanzhengxing'%int(num)*2)
    TypeError: not all arguments converted during string formatting
    >>> #后面有% 没用逗号,而前面没有%,错误

    原图:

    >>> num=input('n:')
    n:1234
    >>> print('sdf:',n)
    Traceback (most recent call last):
      File "<pyshell#72>", line 1, in <module>
        print('sdf:',n)
    NameError: name 'n' is not defined
    >>> print('sdf:',num)
    sdf: 1234
    >>> print('sdf:',int(num))
    sdf: 1234
    >>> print('sdf:',int(num)*2)
    sdf: 2468
    >>> print('sdf:%d',int(num)*2)     #前有%d,后用的逗号,没用%:%d当做字符输出了
    sdf:%d 2468
    >>> print('sdf:%d'%int(num)*2)
    sdf:1234sdf:1234
    >>> print('sdf:%d'%int((num)*2)))
    SyntaxError: invalid syntax
    >>> print('sdf:%d'%(int((num)*2)))
    sdf:12341234
    >>> print('sdf:%d'%(int(num)*2))
    sdf:2468
    >>> 
    >>> print('sdf:'%int(num)*2)      #后面有% 没用逗号,而前面没有%,错误
    Traceback (most recent call last):
      File "<pyshell#84>", line 1, in <module>
        print('sdf:'%int(num)*2)
    TypeError: not all arguments converted during string formatting
    >>> print('sdf:'%(int(num)*2))
    Traceback (most recent call last):
      File "<pyshell#85>", line 1, in <module>
        print('sdf:'%(int(num)*2))
    TypeError: not all arguments converted during string formatting
    >>> 

    #int(num)没括号不行

    >>> print('sdf:%d'%int num*2)
    SyntaxError: invalid syntax
    >>> print('sdf:%d'%int num)
    SyntaxError: invalid syntax
    >>> 

    原图: #int(num)没括号不行;    #字符串*2

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  • 原文地址:https://www.cnblogs.com/hhj187/p/4607180.html
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