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rolox
Joined: 25 Dec 2014 Posts: 33
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sprint(), format parameter via variable |
Posted: Thu Dec 25, 2014 5:04 pm |
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Hello,
how can i pass a formatstring to sprintf() via a variable ?
it only seems to work with constant formatstrings :
Code: | //does not work
char result[10]
char aktformat[10]="%4.1w";
sprintf(result,aktformat,123);
// Outputs only the formatstring itself
// works :
sprintf(result,"%5.1w",123);
//outputs " 12.3" as expected
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tried same snippet with MPLAB XC8 compiler - there it works - but don't really want to switch just because of this issue ...
any hints welcome
greetings
rolox
edit: spent some more time on "search" and found an explanation in a similar topic about 4 years ago, which makes it most likely that CCS did not change this behaviour since then ...i'll have to check to change to integer and use some "itoa" functionality instead |
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Ttelmah
Joined: 11 Mar 2010 Posts: 19513
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Posted: Fri Dec 26, 2014 9:18 am |
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The CCS sprintf/printf, does not support this.
The reason is simple. They only load the code components required, not everything. As soon as you switch to a 'variable' for the functions, they get bulkier, having to load all the parts....
However if you must use a variable, then the open source sprintf, translates quite easily:
<http://www.opensource.apple.com/source/ruby/ruby-67.6/ruby/sprintf.c>
and the small sprintf, is even easier (remember you need 'PASS_STRINGS=IN_RAM', and look at Mark's sscanf implementation in the code library for how to handle variable length arguments):
<http://www.menie.org/georges/embedded/printf.html>
I've used versions of both, but for customers, so I can't post them. |
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rolox
Joined: 25 Dec 2014 Posts: 33
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Posted: Sat Dec 27, 2014 12:38 pm |
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Hello, thx for quick reply ....just had a look at both versions, the second one is tiny - but as far as ic acn see, they do not support the CCS format type "%n.mw" , f.w "%5.1w" which would be the one i'd used most, in some variations like "%5.0w", "%5.1w", "%5.2w".
But even if this is the same Type of format, it will not be possible to change it during runtime - probably the solution is "diy" ;-) |
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Ttelmah
Joined: 11 Mar 2010 Posts: 19513
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Posted: Sat Dec 27, 2014 3:44 pm |
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Or just add the w format to the code. There is nothing terribly 'magic' about it.
Remember that you could sprintf to a string, without any decimal point, and then just use the string functions to add this at the location you require. |
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rolox
Joined: 25 Dec 2014 Posts: 33
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Posted: Sun Dec 28, 2014 6:10 am |
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you're absolutely right. I'm pretty new to CCS and try to use as much existing as possible - the difficulty is often to find the right time to stop searching and switch to writing it yourself :-)
Thanks a lot for pointing out the possibilities ! I'll have some time now ...it's heavily snowing here , preventing me from moving in front of the door .... |
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