[Tutor] reiterative programming

[Lloyd Kvam]

You might find it easier to code against the integer that ord(c)
returns and delay converting to hex until you actually need to use
the hex value.

returnedval = None
while returnedval != 4:
	output=port.read(1)	# using 1 was suggested by someone else
	returnedval= ord(output)

In those places where you need the hex value, you would specify:
	hex(returnedval)

This avoids "fussy" string comparisons. (e.g. '0x4', '0X4', '0x04')

Stanfield, Vicki {D167~Indianapolis} wrote:

> No, I want the hex version of the ASCII representation. It is what the item on the other end wants. I don't know why they do it that way, but if I want to talk to their device, I have to do it that way. At least you give me hope that the awkwardness I perceive is not simply my perception.
> 
> --vicki
> 
> -----Original Message-----
> From: Alan Gauld [mailto:alan.gauld at blueyonder.co.uk]
> Sent: Monday, October 27, 2003 1:52 PM
> To: Stanfield, Vicki {D167~Indianapolis}; tutor at python.org
> Subject: Re: [Tutor] reiterative programming
> 
> 
> I'm not sure I understand the logic of the conversion.
> 
> hex(ord(c))
> 
> takes the character c, converts it to a number equal
> to its ASCII value and then turns that number into a
> hex representation. (Try it in the interpreter:
> 
> 
>>>>print ord('4')
> 
> 52
> 
>>>>print hex(ord(4))
> 
> 0x34
> 
> Are you sure you don't want the hex representation of
> the number the character represents
> 
> 
>>>>print hex(int('4'))
> 
> 0x4
> 
> Or even
> 
> 
>>>>print int('4',16)
> 
> 4
> 
> 
>>I want to loop through doing this until the returned value is a hex
> 
> 4.
> 
>>while returnedval != '\0x4':
> 
> 
> This checks for the string '\0x4' which treats the \ as an escape
> and yields:.
> 
> 
>>>>print '\0x4'
> 
>  x4
> 
> You could use a raw string:
> 
> 
>>>>print r'\0x4'
> 
> \0x4
> 
> 
>>For some reason that I don't understand, when the returnedval
>>is '0x4', it does the loop again
> 
> 
> Because '0x4' is not the same as '\0x4'!
> 
> You need to be very clear about what you actually want to compare
> with what, and then check the actual format you are using.
> The >>> prompt is your friend.
> 
> Alan G.
> 
> 
> 
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-- 
Lloyd Kvam
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