[Tutor] Times Tables Program that constantly tells you that you are wrong!

[Matthew Polack]

Thanks Alan and Peter for all your help with this.

I got it all to work..thank you..

like learning a musical instrument...probably just need some time
consolidating the current skill set...has been a lot to take in...

but getting there steadily...and bit by bit it is starting to make sense..

I'll probably stick with the traditional  %. method too for a while because
that is now what I understand.

thanks...will keep trying things..and then also reading through the various
docs provided...+ your emails.

Thank you.






Matthew Polack | Teacher


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On Thu, Aug 23, 2018 at 10:34 PM, Alan Gauld via Tutor <tutor at python.org>
wrote:

> On 23/08/18 06:10, Matthew Polack wrote:
>
> > I'm also trying to solve the rounding issue...but can't work out the
> syntax
> > using the example provided...have tried this but I get an error...
> >
>
> > def viewPercent():
> >      percentCalc = score/total*100
> >      percentViewLab["text %.2f"] % percentCalc
>
> OK, the problem here is mixing up your data with TKinter's
> (inherited from Tcl/Tk) mechanism for accessing widget
> attributes.
>
> percentViewLab["text %.2f"]
>
> This tells Tkinter to fetch an attribute of your widget
> called "text %.2f". Of course there is no such attribute,
> it is called just "text".
>
> percentViewLab["text %.2f"] % percentCalc
>
> This tries to insert the percentCalc value into the
> string returned by the widget.
>
> Again that's not what you want. You want to insert
> the data into a string which will then be assigned
> to the widget's text attribute.
>
> val = "%.2f" % percentCalc  # eg. -> val = "0.76"
>
> Now insert val into your widget
>
> percentViewLab["text"] = val
>
> or equivalently:
>
> percentViewLab.config("text", val)
>
> You can of course combine all of that with
>
> percentViewLab["text"] = ".2f" % percentCalc
>
> Personally I tend to separate the creation of the
> string from the widget assignment because it makes
> it easier to debug by printing the string to the
> console.
>
> One final note. When using % to inject data into
> a format string you MUST put the percent immediately
> after the format string. No commas or parentheses
> allowed.
>
> The % formatting style is preferred by old school
> programmers (like me) who came from the world of C and
> its relatives because C uses a very similar style in
> its printf() family of functions. However, new programmers
> may find the format() method of a string more obvious.
> (I'm thinking about your students here)
>
> Using format your case would look like:
>
> val = "{:.2f}".format(percentCalc)
>
> And the previous example would be:
>
> fail_str = """
> Sorry, you got it wrong,
> the correct answer was {:d}
> Your current score is: {:f}""".format(answer,score)
>
> It is quite similar except the placemarkers are {}
> and you call the format() method. The formatting
> characters inside the {} are different too - you
> need to read the docs... There are zillions of examples.
> You might find it more logical.
>
> --
> 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
>
>
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