topic Re: Pointer problems in Classic/Legacy CodeWarrior

Pointer problems

NZ_Design — Tue, 28 Nov 2006 06:41:41 GMT

I have used the ICC compiler in the past and are changing my code over into CW.

One line I are haveing trouble with it is one I use all the time.

I have a string decleared

#define S_TABLANE      "LANE\0"
#define S_TABOUTLET    "OUTLET\0"
#define S_TABSIZE      "SIZE\0"
#define S_TABAVGSIZE   "PACKS\0"

I then have an array that points to each of these strings.

const char* TabName[] = {S_TABLANE,S_TABOUTLET,S_TABSIZE,S_TABAVGSIZE};

in my old code I accessed this by doing this

gputs(TabName[cTab]);

That would display the required string this on longer is the case. The screen displays rubish and it is in a never ending loop. Never finds the end of the string.

To get round it I did a switch case statement which works

   switch (cTab) {
     case 0:
       gputs(S_TABLANE);
       break;
     case 1:
       gputs(S_TABOUTLET);
       break;
     case 2:
       gputs(S_TABSIZE);
       break;
     case 3:
       gputs(S_TABAVGSIZE);
       break;
   }

why does CW not like my pointer array.

Re: Pointer problems

CompilerGuru — Tue, 28 Nov 2006 18:39:57 GMT

This partial coded snipped you are showing looks ok, it should work with CW too.
Without a full compilable sample showing the problem it is impossible to say.
Some notes anyway:

>const char* TabName[]

This is a non constant array, therefore you have to have the startup code to initialize it properly. Do you have start12.c in your project? (or start08.c, if this is for the HC08).

Probably you should change this to:

const char* const TabName[]

so it would end up in flash and not use RAM.

>#define S_TABLANE      "LANE\0"

The ANSI-C standard adds a 0 byte at the end of every string literal for you. When you add one explicitly like this, you will end up with two 0 zero bytes at the end.

So if this does not help, the best would be to post a zip file with a complete project showing the problem. As the startup code note shows, the problem may be somewhere else than directly in the C file too.

Daniel

Re: Pointer problems

NZ_Design — Wed, 29 Nov 2006 04:08:35 GMT

Thanks for your help. That worked however the first const is not required as this brings up a warning.

Re: Pointer problems

CompilerGuru — Mon, 02 Nov 2020 14:46:13 GMT

The first const is not strictly necessary, but I would write it. It says that the string literals cannot be changed, and as the do by default end up in flash, that's just the truth....

Warnings about different const qualifiers are often caused by missing const qualifiers, not by having too many of them, at least this is my experience with existing code and const's.
Does the prototype of gputs contain a const?

void gputs(const char*);

Well, otherwise you would have to show the warning and the code generating it. But as it works now maybe that good enough too

Daniel