《Python核心編程》P21輸入數值字串→轉整型

標籤：

>>> 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，後用的逗號，沒用%：%d當做字元輸出了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)      #後面有% 沒用逗號，而前面沒有%，錯誤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>>> 

 

原圖：

 

#int（num）沒括弧不行

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

原圖： #int（num）沒括弧不行；    #字串*2

《Python核心編程》P21輸入數值字串→轉整型