Hello seniors,
I am beginner in Palm OS programming and have a basic
background of C++. I faced problem while creating a
very simple application that performs
storing/retrieving data to/from Palm. The application
should be able to accept data for two fields (Name &
Note). Then retrieve it back on screen. The
application has successfully add a new record.
However, error occurs when retrieving the record at
UnPackRecord method. I have been trying to solve this
problem for 3 days. However, I couldn't manage it. I
really appreciate your help.
Here are the codes:
typedef struct
{
Char* Name;
Char* Note;
} testRecItem;
typedef struct
{
char NameNote;
}testRec;
typedef testRecItem* testRecItemPtr;
typedef testRec* testRecPtr;
//*************************************************************************
static void ShowRecord(UInt16 index)
{
MemHandle recordH;
testRecPtr recordP;
testRecItemPtr record;
recordH = DmQueryRecord(testDB, index);
if (recordH != NULL)
{
recordP = MemHandleLock(recordH);
UnPackRecord(record, recordP);
MemHandleUnlock(recordH);
SetText(GetObjectPtr(MainNameField), record->Name);
SetText(GetObjectPtr(MainNoteField), record->Note);
}
}
static void UnPackRecord( testRecItemPtr record,
testRecPtr src )
{
Char *p;
p = &src->NameNote;
//The error occurs just right here
record->Name = p;
p += StrLen(p) + 1;
record->Note = p;
}
static void PackRecord( testRecItemPtr record, MemPtr
recordP )
{
Char zero=0;
testRecPtr nilP=0;
MemPtr p;
UInt16 length;
UInt32 offset;
offset = (UInt32)&nilP->NameNote;
if ( record->Name )
{
p = record->Name;
length = StrLen(p) + 1 ;
DmWrite( recordP, offset, p, length);
offset += length;
}
else
{
DmWrite( recordP, offset, &zero, 1 );
offset++;
}
if ( record->Note )
{
p = record->Note;
length = StrLen(p) + 1 ;
DmWrite( recordP, offset, p, length);
}
else
DmWrite( recordP, offset, &zero, 1 );
}
static UInt16 GetPackedSize(testRecItemPtr record)
{
UInt16 size;
size = sizeof(testRec);
if (record->Name)
size += StrLen(record->Name) + 1;
if (record->Note)
size += StrLen(record->Note) + 1;
return size;
}
static void AddNewRecord(void)
{
MemHandle recordH;
testRecItemPtr newRecord;
testRecPtr recordP;
UInt16 index = DmNumRecords(testDB);
newRecord->Name =
FldGetTextPtr(GetObjectPtr(MainNameField));
newRecord->Note =
FldGetTextPtr(GetObjectPtr(MainNoteField));
recordH = DmNewHandle(testDB,
GetPackedSize(newRecord));
recordP = MemHandleLock(recordH);
PackRecord(newRecord, recordP);
MemHandleUnlock(recordH);
DmAttachRecord(testDB, &index, recordH, 0);
FrmCustomAlert(MsgAlert, "New record has been added",
NULL, NULL);
}
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