There is another way to deal with this that would be better
(IMO ... I hate being responsible for deallocating memory
that somebody else allocates.) :
make the temp char array static -- then it sticks around
even when the function is done
--
-Richard M. Hartman
[EMAIL PROTECTED]
186,000 mi/sec: not just a good idea, it's the LAW!
Al Cilcius wrote in message <29825@palm-dev-forum>...
>
>Your function below, IntToStr, is flawed. Look at it again:
>
>CharPtr IntToStr(Word num)
>{
>
> Char ptext[7];
> CharPtr ptemp;
>
> ptext[0]='\0';
> ptemp = StrIToA(ptext, num);
>
> return(ptemp);
>}
>
>You are returning a pointer to a char array allocated on the stack. Thus,
>when the return statement is "executed," ptemp (the resultant returned
>pointer) is pointing to deallocated memory (and is now garbage). Sometimes
>this will work, and sometimes this will not. This is what I call "running
>by luck." IntToStr should be re-written to something like this:
>
>CharPtr IntToStr(Word num)
>{
> CharPtr ptemp;
> ptemp = MemPtrAlloc(16);
>
> return (StrIToA(ptemp, num));
>}
>
>The caller of this routine will be responsible for eventually calling
>MemPtrFree on the returned pointer.
>
>-----Original Message-----
>From: [EMAIL PROTECTED]
>[mailto:[EMAIL PROTECTED]]On Behalf Of
>Nesselhauf, John
>Sent: Friday, November 10, 2000 12:59 PM
>To: Palm Developer Forum
>Subject: RE: An issue of scope???
>
>
>I believe you must think in terms of where is the variable pointing to when
>the 2nd function SetTextToField is placed on the stack. It is obviously not
>pointing at the same location. I am no expert in this but if you approach
it
>from that aspect it may help you determine a correct course of action. Make
>sure that what is being passed back from IntToStr is a CharPtr. Also, you
>may want to try Locking and Unlocking memory on the variable that is being
>passed.
>
>Hope this helps.
>
>John N.
>
>-----Original Message-----
>From: Matt Becker [mailto:[EMAIL PROTECTED]]
>Sent: Friday, November 10, 2000 10:09 AM
>To: Palm Developer Forum
>Subject: An issue of scope???
>
>
>Another question for everyone. The following line calls the
>SetTextToField function, described below. Inside this call, it also
>calls IntToStr, as you can see. Now, these 2 functions are in a
>different file than the call.
>1st. The call to IntToStr is passed a number, and it sucessfully passes
>the resultant string back to file1 and sets pnumstr to the string passed
>back. Now, when SetTextToField is called, the value passed into it is
>random! Why would pnumstr get miss-passed? Its like its not passing
>the value into SetTextToField whatsoever. The value of pnumstr is,
>according to the debugger, correct. But, when the programs shifts to
>the SetTextToField function, the value of ptext that is passed in is
>garbage. Is this an issue of scope? If so, then why doesnt
>MyNum.Number sucessfully get passed into, and back out of IntToStr,
>which is in the same file as SetTextToField. Please help. thanks!
>
>
>file1.c
>CharPtr pnumstr;
>pnumstr = IntToStr(MyNum.Number);
>SetTextToField(ReviewNumField, pnumstr );
>
>
>
>file2.c
>void SetTextToField( Word fieldID, CharPtr ptext )
>{
> FormPtr pform;
> FieldPtr pfield;
> VoidHand hfield;
> CharPtr pfieldtext;
>
> pform = FrmGetActiveForm();
> pfield = FrmGetObjectPtr(pform, FrmGetObjectIndex(pform, fieldID));
> hfield = FldGetTextHandle(pfield);
> if(hfield != NULL)
> {
> MemHandleResize(hfield, StrLen(ptext)+1);
> }
> else
> hfield = MemHandleNew(StrLen(ptext)+1);
> pfieldtext = MemHandleLock(hfield);
> StrCopy(pfieldtext, ptext);
> MemHandleUnlock(hfield);
> FldSetTextHandle(pfield, hfield);
> FldDrawField(pfield);
>
> return;
>}
>
>CharPtr IntToStr(Word num)
>{
>
> Char ptext[7];
> CharPtr ptemp;
>
> ptext[0]='\0';
> ptemp = StrIToA(ptext, num);
>
> return(ptemp);
>}
>
>
>
>
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>
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>
>
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