Oliver Ott wrote:
I searched through the Reference especially the String Manager
chapter to find a function I used before with MS VBA.
Syntax
Replace(expression, find, replace[, start[, count[, compare]]])
This function for Visual Basic replaces a char by another char.
Doesn't exist in Palm OS. However, you can use a loop to do it:
void strreplace (Char *str, Char old, Char replacement)
{
Char *c;
for (c = str; *c != 0; c++)
{
if (*c == old)
{
*c = replacement;
}
}
}
That will only replace one character with another, not a whole set.
Syntax
Split(expression[, delimiter[, limit[, compare]]])
The usual way to do this in C is to use strtok(). However, I don't
think that the Palm has an equivalent for that function. So, you'll
have to do that manually, too.
If you want to do it strtok() style, strtok() works by taking
advantage of the fact that C strings end with a null (zero) character.
So, you can split a string by writing a null character into the
middle of it, then taking the pointer to the spot after you write
the null (assuming there is such a spot).
For example, "12.34" is actually stored like this (with made-up
memory addresses to make the pointer stuff clearer):
"1" "2" "." "3" "4" null
5000 5001 5002 5003 5004 5005
You can split it by writing a NULL into location 5002 and taking
a pointer to location 5003:
"1" "2" null "3" "4" null
5000 5001 5002 5003 5004 5005
Thus, you can write a function to find the first delimiter
character, replace it with a null, and then return a pointer
to the stuff after it. You can call this function repeatedly
to process each delimiter character and turn it into a null.
For example:
Char* replacedelimiter (Char *targetstr, Char delimiter)
{
Char *delimiterlocation;
for (delimiterlocation = targetstr;
*delimiterlocation != 0;
delimiterlocation++)
{
if (*delimiterlocation == delimiter)
{
/* change delimiter to 0 */
*delimiterlocation = 0;
/* return location after what we just changed to
null, which is the rest of the string */
return (delimiterlocation + 1);
}
}
/* we hit the end of the string without finding
the delimiter, so return NULL to indicate that */
return NULL;
}
Once you have a function like that, you can just call it in a loop
until it returns NULL. Of course, you have to make sure that the
string you pass it can be written to. (You can't legally pass it
a constant string. For instance, you couldn't legally do
replacedelimiter ("12.34", '.') beceause the inline "12.34" is
a constant. But, the compiler should warn you about this in
many cases if you make that mistake.)
Anyway, a loop to show all the pieces of the string might look
like this:
Char *piece;
Char *remainder;
Char tobesplit[] = "1-800-555-1212";
remainder = tobesplit;
do
{
piece = remainder;
remainder = replacedelimiter (remainder, '-');
FrmCustomAlert (MyAlert, piece, "", "");
} while (remainder != NULL);
The above code is a little confusing because piece and remainder are
set to the same pointer value (same location in memory), and then
replacedelimiter() changes that memory, and only after it has changed
is it true that piece points to a piece, because although it's always
pointing to the same place, the null terminator hasn't been written
into memory to break it apart yet.
- Logan
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