OpenEuphoria

Re: Undocumented "printf()" funnies

• Posted by Chris Burch <chriscrylex at aol.com> Feb 04, 2005
• 447 views

Alan Oxley wrote:
> 
> Hi, some observations with Eu 2.5a:
> 
> If you leave out the "%" symbol in a printf, then its not an error,
> you simply get the string within the quotes printed. Would it not be better
> to either document this, or have euphoria return "Unknown printf format"
> as it does if you tried printf(1,"%k",0) Where "%k" is the rubbish demo.
> 
> Most incorrect formatting attempt within the printf quotes is not picked up
> by initial parsing, only at execution time. Since you cannot use variables
> within the quotes, there is no reason not to have this parsed? 
> 
> Attempting to use two decimal places is also unsupported, but it does
> not give a parse error, but simply a strange result:
> 
> }}}
<eucode>
> atom a
> a = 100000001
> printf(1,"%3.3.3d",a) 
> </eucode>
{{{

> will display ".3ld"  (Where does the "l" come from?)
> 
> This is also the case with eu2.4 official.
> Yes, I know I can get the result I want with multiple printf's but this is
> to demonstrate the problem. I also know that pretty print is not printf!
> 
> Regards,
> Alan
> 


Hi

Thats normal behaviour, and how its supposed to work, in fact its a 'cut down'
version of c fprintf

the % tells the parser there's a formatting character coming
the 'd' 's' 'f' tell it the type (there is no 'c' in eu)
the numbers inbetween tell it how to print it
eg

printf(1,"%d", {12})
12

printf(1, "%03d", {12})
012

printf(1, "%10s", {"Hello"})
     Hello

printf(1, "%-10s%-10s", {"Hello", "World"})
Hello     World

printf(1, "%-14.14s", {"Hello world its a nice day isn't it"} )
Hello world it

printf(1, "%8.2f\n8.2f", {123.5678567, 45.897565432})
  123.56
   45.89

etc.

If a formatting character isn't found after a number its ignored, hence
%3.3.3d
is basically just ignored, and I've no idea where the l comes from!
(Probably just garbage)

if you want a % sign, then use 2 together

Chris




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