On 01/06/16 12:43, marat murad via Tutor wrote: > Thanks for your replies,I think I understand it much better now. I Also I > wanted to know what the 'None' does in the second program.
Please make the subject something meaningful and delete all the excess messages. we have all seen them already and some people pay by the byte. As for none, it just means a reference to nothing. ie no object. So in your example: start= None while start != "": start=input("\nStart: ") ... The start = None could have been replaced by anything other than an empty string. It just creates an initial value that causes the while loop to start. You will often find None used like this: to create a named value that has no significance at that point in the program but will be used later. Another way of writing your example would be: while True: # loop forever start = input(...) if start = "": break # break exits the nearest loop ... HTH -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ http://www.amazon.com/author/alan_gauld Follow my photo-blog on Flickr at: http://www.flickr.com/photos/alangauldphotos _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor