Robert Kern wrote:
> flyaflya wrote:
>
>> from random import *
>>
>> col = [0 for i in range(10)]
>> a = [col for i in range(10)]
>
>
> This is the problem. The list "a" now has ten references to the same
> object "col". They are not copied.
>
>> seed()
>> for i in range(10):
>> for j in range(10):
>> a[i][j] = randint(0, 100)
>
>
> So every time you index into "a[i][j]" you are always getting "col[j]".
>
thanks,I see,I know about reference and copy,but when is it a copy?when
a reference?how can I get a copy when need?
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