On Wed, 16 Jan 2008 13:59:03 +0800, J. Peng wrote: > Hi, > > How to modify the array passed to the function? I tried something like > this: > >>>> a > [1, 2, 3] >>>> def mytest(x): > ... x=[4,5,6]
This line does NOT modify the list [1, 2, 3]. What it does is create a new list, and assign it to the name "x". It doesn't change the existing list. If you have not already done this, you should read this: http://effbot.org/zone/python-objects.htm Consider this function: def test(alist): alist.append(0) # this modifies the existing list alist = [1, 2, 3] # this changes the name "alist" return alist Now try it: oldlist = [10, 9, 8, 7] newlist = test(oldlist) Can you predict what oldlist and newlist will be equal to? oldlist will be [10, 9, 8, 7, 0] and newlist will be [1, 2, 3]. Do you see why? -- Steven -- http://mail.python.org/mailman/listinfo/python-list
