C++ is fun monkey fun.

Question

map listOfPlayers; extern C bool R_CONTROLLER_API CreatePlayer(int num) { Player * Player1 = new Player(num); listOfPlayers[num] = Player1; return true; } extern C R_CONTROLLER_API char *ListPlayers() { static char string2return[500]; *string2return=0; for( map ::iterator i=listOfPlayers.begin(); i != listOfPlayers.end(); i++) { strncat(string2return test  + (*i).first __min( 20 500-strlen(string2return)) ); //params: char array char array to append number of chars to append //__min returns the lesser of 2 numbers } return string2return; } The code above compiles fine and CreatePlayer() works great but the problem I'm having is in ListPlayers(). When invoked the only thing I get back from the function is est  with no 't'. I really suck with C++ so I'd appreciate the help!

Adam Turner · Answer

Well after some monkeying around in another forum I was able to divulge a few things about how my code should look. It now properly converts ints to chars and uses ostringstream to output the text correctly without cutting anything off. The problem has become that the global map variable isn't expanding in size (I know globals are bad) I haven't been able to determine why this is. At first I thought it was simply an iterator bug but I tested the map's size and found that it hasn't expanded. It seems to allow the first assignment of a player although maybe it's crashing even there because the int returns 1 no matter what number is inserted. It never allows for another insertion of a player. static map listOfPlayers; extern C bool R_CONTROLLER_API CreatePlayer(int num) { Player * Player1 = new Player(num); listOfPlayers[num] = Player1; return true; } //a char array is the same as a char * in partiality because they are both represented by a start at a certain memory address extern C R_CONTROLLER_API char *ListPlayers() { ostringstream string2return; static char buf[500]; *buf=0; int count=1; for( map ::iterator i=listOfPlayers.begin(); i != listOfPlayers.end(); ++i) { string2return string2return count++; //params: char array char array to append number of chars to append //__min returns the lesser of 2 numbers } strcat(bufstring2return.str().c_str()); //concatenate a C style string with a char array return buf; }

Alan · Answer

Assuming it's a console app I'd insert this line just before the C++ function returns to see what's actually in the string: printf(%s  string2return); I can't see any obvious problem with the iterator which should print out successive player numbers preceded by test .

Adam Turner · Answer

Here's the code from a small game engine/language called BYOND that I'm using to call it from: verb/Create_Player(var/n as num) if(call(R_Controller.dllCreatePlayer)(n)) usr verb/List_Players() var/s = call(R_Controller.dllListPlayers)() usr Create_Player() returns successfully. But List_Players() shows est  only once regardless of how many players are created. I originally had List_Players() set up as just usr So just adding another char to the string would solve my problem for the est  but perhaps the more disturbing glitch is the fact that the list is only iterated through once. Any ideas?

Alan · Answer

Well I'd change this line: static char string2return[500]; to this: static char string2return[501]; to allow for the terminating null character which strlen doesn't include when calculating the length. However even as it stands I can't see any reason why you're losing the first character of test  in the function return value. Are you sure that you're not losing it later when you print it out - perhaps printing from index 1 rather than index 0 something like that?

C++ is fun, monkey fun.