CCS C Software and Maintenance Offers
FAQFAQ   FAQForum Help   FAQOfficial CCS Support   SearchSearch  RegisterRegister 

ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

CCS does not monitor this forum on a regular basis.

Please do not post bug reports on this forum. Send them to support@ccsinfo.com

Printf formatting....

 
Post new topic   Reply to topic    CCS Forum Index -> General CCS C Discussion
View previous topic :: View next topic  
Author Message
JAM2014



Joined: 24 Apr 2014
Posts: 138

View user's profile Send private message

Printf formatting....
PostPosted: Wed Jun 23, 2021 2:51 pm     Reply with quote

Hi All,

I have an signed int8 variable that varies from -10 to +10. I'd like to display the value exactly this way using the printf function. Is there a format specifier that will allow me to do this in a single line? Currently, I need to do this in two lines depending on whether the value is less than 0 or not.
Code:

if (UTCOffset < 0){
               sprintf(TempTimeStr,"PageSetup.txtUTCOffset.txt=\"%03d\"", UTCOffset); SendNextionValue(TempTimeStr);
            }
            else{
               sprintf(TempTimeStr,"PageSetup.txtUTCOffset.txt=\"+%02d\"", UTCOffset); SendNextionValue(TempTimeStr);
         }


This is not a huge deal except I have other similar variables that I'd like to do in the same way, and the code is getting a bit 'messy'!

Edit: Changed description of variable type!

Thanks,

Jack


Last edited by JAM2014 on Wed Jun 23, 2021 5:51 pm; edited 1 time in total
temtronic



Joined: 01 Jul 2010
Posts: 9081
Location: Greensville,Ontario

View user's profile Send private message

PostPosted: Wed Jun 23, 2021 5:24 pm     Reply with quote

hmmm...
Quote:
I have an unsigned int8 variable that varies from -10 to +10.

me thinks you have a SIGNED int8 variable...
Ttelmah



Joined: 11 Mar 2010
Posts: 19195

View user's profile Send private message

PostPosted: Wed Jun 23, 2021 11:55 pm     Reply with quote

Yes.
However the problem he is having is down to CCS missing one of the standard
C format flags.
By default a number displays a leading - if negative, but nothing if positive.
There was a flag defined in K&R, that + could be used in front of the
width specifier, and if this existed, the formatter would display + if positive
and - if negative. This though is not supported in CCS. Sad

Suggestion. Create a function to do it. So:
Code:

char * string_with_sign(signed int8 val)
{
   static char buffer[4]; //remember need to be space for NULL as well
   //also must be static so can be returned
   if (val< 0)
   {
        sprintf(buffer,"%03d", val);
   }
   else
   {
        sprintf(buffer,"+%02d", val);
   } 
   return buffer;
}

//Then when you want to print the value, use this and %s
   sprintf(TempTimeStr,"PageSetup.txtUTCOffset.txt=\"%s\"", string_with_sign(UTCOffset)); SendNextionValue(TempTimeStr);


Now this can then be used for other values. It just generates a 3 character
'string' containing the number formatted as required.
JAM2014



Joined: 24 Apr 2014
Posts: 138

View user's profile Send private message

PostPosted: Fri Jun 25, 2021 7:42 am     Reply with quote

Hi All,

Temtronic: Thanks for pointing out the error in my OP!

Ttelmah: That is perfect! Exactly the idea I was looking for!

Thanks,

Jack
Ttelmah



Joined: 11 Mar 2010
Posts: 19195

View user's profile Send private message

PostPosted: Fri Jun 25, 2021 8:02 am     Reply with quote

I've actually suggested to CCS, that they might want to consider adding the flags. There are two. + for leading plus, and - for left justify in the output
field. They are C features that at time can be useful.
I knew exactly what you were saying, since I had found this myself some
time ago.... Sad
JAM2014



Joined: 24 Apr 2014
Posts: 138

View user's profile Send private message

PostPosted: Fri Jun 25, 2021 11:26 am     Reply with quote

Hi All,

As a quick follow-up, a CCS fix would be nice, but in the meantime....

I was thinking that a more universal fix might be desirable that could accommodate different width variables. At the moment, I have both -10 to +10, and -125 to +125, so I currently need at least two formats. I have passed a 'count' variable to the new function, and handle things differently depending on a count of '2' or a count of '3', but it would be nice to have something more flexible. I haven't found a way to make the format specifier, eg. "+%02d", use a variable. How could that be done neatly/cleanly?

Thanks,

Jack
jeremiah



Joined: 20 Jul 2010
Posts: 1314

View user's profile Send private message

PostPosted: Fri Jun 25, 2021 1:16 pm     Reply with quote

JAM2014 just make sure not to use that function in other code without ensuring that the values are between -99 and +99 or it will overwrite memory. Once the values hit 3 digits your string variable inside the function needs to be at least a size 5 (currently a size 4) to hold the 1 digit sign, a 3 digit number, and the null character.

You could adjust it to be a 5 byte string and then you can use it universally.
Display posts from previous:   
Post new topic   Reply to topic    CCS Forum Index -> General CCS C Discussion All times are GMT - 6 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group