Damn strings and pointers!

[Nobody/Anonymous]

Damn strings and pointers! I just can't get it right.

Suppose this:

MessageBox(NULL, "You have made this error x times", "Error", MB_OK);

now I want to replace x with some counter:

LPTSTR ModString(LPTSTR line)
{
   counter ++;
   // chage line so x is replaced by counter
  return line;
}

and then I go:

MessageBox(NULL, ModString("You have made this error x times"), "Error", MB_OK);

..and it doesn't work. It does work when I do this:

LPTSTR ModString(LPTSTR line)
{
   counter ++;
   char *temp = new char(strlen(line));
   // strcpy line into temp
   // chage temp so x is replaced by counter
   return temp;
}

But when I loop this function I run out of memory in no time, which makes sense because 'new' is never deleted.

What should my ModString function look like for this to work?

-Jay

[Nobody/Anonymous]

hmmm... I don't have a link on me... but there is an excelent post by tkorrovi that does something very similar... i would highly suggest you search the forum for his name plus winmain and/example...

Zero Valintine

[upcase]

This may be a stupid question since I don't do alot pure win api programming, but wouldn't wsprintf() fullfill your needs? Just a guess...

[Patrick Ogay]

as I see, you just need the function in the messagebox.

LPTSTR is, as I remember dependent of the definiton _UNICODE it's characterstring either char or wchar..
if you work with char you never work with wide character anyway, so you could use:

static string outfield   /* so you reuse your string */
return outfield.c_str();

I'm even not shure, whether the string must be static, as you just use it, after return.

Patrick

[Curtis Sutter]

MessageBox(NULL, ModString("You have made this error %d times"), "Error", MB_OK);

LPTSTR ModString(char line[])
{
  char temp[] = "You have made this error %d times";
  sprintf(line, line, counter++);
  return line;
}

Maybe somethiing like this would work better for you?  I am unfamilier with the LPTSTR type, so the return maybe buggy.  This can be fixed though I'm sure.

Curtis

[Nobody/Anonymous]

Patrick you are right. This is what I did:

LPSTR ModString(string line)
{
counter ++;
// chage line so x is replaced by counter
LPSTR abc = (LPSTR)line.c_str();
return abc;
}

this does not even depend on char or whar, because it is possible to do something like this:

typedef std::basic_string<TCHAR> tString;

and then use tString where it says string.

My problem is now: WHY does this work (and the previous not)?

-Jay

[Nobody/Anonymous]

Thanks Curtis. At least I now know how that sprintf thing works. But, as you suspected, the return fails. It compiles ok, but when I run I get a memory allocation error.

Zero Valentine, I have only found one tkorrovi post with the search criteria you mentioned and I can't see anything relevant there... thanks anyway.

-Jay

[Nobody/Anonymous]

Curtis,

on second thought.. what's that char temp[] for?
1. It isn't used and 2. it is identical to line

-Jay

[Curtis Sutter]

I was in a hurry, disregard that line.  Sorry, I should have dbl checked my post.

Curtis