Problem using printf to print string variables

Peter F · Joined: 12 Feb 2004 Posts: 9 Location: Surrey, UK

I am using

printf("%S",StringData);

where StringData is a string variable (character array with null terminator)

What I get on the RS2323 output is only the last two characters!

For instance, if I load StringData as follows:

StringData[0]=0x31; //ASCII 1
StringData[1]=0x32; //ASCII 2
StringData[2]=0x33; //ASCII 3
StringData[3]=0x34; //ASCII 4
StringData[4]=0; //null

Output is 34

If I use the form

printf("1234");

Then I get 1234 as expected.

Anyone any idea what's going on? I have checked the file registers and the string variable is correctly loaded, so why does it ignore all but the last 2 characters? Confused

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

The following program works fine with PCM vs. 3.184.
It displays this: 1234

Peter F · Joined: 12 Feb 2004 Posts: 9 Location: Surrey, UK

Thanks for that! My code is exactly the same. Only differences are that I am using PCH with the 18F452 chip. Using puts(StringData); gives the same result. I have emailed CCS to see if they can help. If I can't find a way out, I will have to write my own function to output strings.

BrunoC12 · Joined: 25 May 2017 Posts: 4

I have the same problem. The program doesn't print all of the values that i define on printf.

Ttelmah · Joined: 11 Mar 2010 Posts: 19224

Are you just losing the last couple of characters?.

If so, not the same problem.

What is happening, is your code drops 'off the end', and the characters still waiting to be sent, then get lost.

Look at PCM_programmer's example in this thread. The 'while' at the end of the code is to prevent this happening.

You have to realise that with embedded code, there is no 'OS' sitting outside the code, waiting to handle things when you leave. The code you write is _everything_. If your code runs out the end, then there is nothing there 'left' to do jobs at this point....