I know a simular problem has already been discussed here but those answers only aplied when passing to libraryfunctions. What if I want to pass on the arguments to one of my own functions? Heres what I meen:

//This one formats the output and returnes the string
char* MyFormatFunction(char *input, ...) {
  va_list valist;
  va_start(valist,input);

  int length=512; //should be enough, havn't come up with a better solution
  char* str=(char*) malloc(length);
  vsnprintf(str,512,input,valist);
  va_end(valist);
  return str;
  };

char* MyPreProcessorFunction(char* input, ...) {
  //
  //I do some stuff with the input string here
  //
  
  char* str=MyFormatFunction(input, ...) // <- how do I pass on the arguments?
  return str;
  };

I know I could make MyFormatFunction take a va_list as the second argument but then I wouldnt be able to call it directly in ordinary printf style. You might also wonder why on earth I would declare a new function like MyFormatFunction when what it does basicly can be sumerized in just two lines of code (malloc and vsnprintf). To tell you the truth I cant remember right now :P. But I know it was necessery. One reason I can think of now is that I wanted to wrap all my output functions with a nice prefix and I wanted MyFormatFunction to be a part of that group. Thanks in advance for any replies. /ThunderSky

Quote:
You need to break MyFormatFunction into two functions, just like printf/vprintf and similar library functions. Then, have the variadic version call the one that takes a va_list parameter.

Thanks Fruny, quite simple, this shows that I still have a lot to learn...

Quote:
Hard-coded buffer sizes = evil.

I dont like that "should be enough", and whats even wors is that I have no error checking yet either. But as I understand it the implementations of sprintf and related functions seldom comply with the standard so I cant really be sure if will return the buffersize needed if an error occurs.

I read that there is a specific function that doesnt acctually return the formatted buffer, but the size that would be needed to store it. Unfortunatly, it seems to be IDE dependent. I got hold of the VC version on microsofts developer pages but Im using DevC++ (MinGW) so that didnt help much. I later found that there is a g++ version (MinGW is a g++ compiler right?). But when I tried to compile whith the g++ version DevC++ said it was undeclared so...Im cinda lost. If you know how to solv the problem, great! otherwise I think Ill just leav it. Not verry nice, but it'l be enough for what Im using it for.

Quote:
Returning new'd string buffers like that is IMO evil as well, unless you have a clear understanding of who owns the string and therefor who is responsible for cleaning it up, or if you return a smart pointer to the buffer.

yeah I know..guess Im just an evil cinda guy...(whats a smart pointer?)


Edit. Forgot the thank you guys for the comments so..thanks

Quote:
Since you're already using C++

Well I guess I do, but I have no idea (well some idea) of how to use classes and a lot of the other C++ stuff. Havnt got the time or strength to read up on the subject... so I tend to stick to the more basic C. for now.

besides, Im using this for a small chat program so I prefer not to use any nonstandard libraries.

Which brings me to another thing Ive been meaning to ask about. If I include a file, say string.h, how much does the final executable grow in size. would it be better to do a

for(i=0;buffer!='\0';i++);

instead of including the whole string.h file and using strlength?

Mainly Im asking because windows.h is huge when you count in all the other files it inculdes and I like to use Sleep() in my simpler console apps and I read somewhere that that could be acheaved some other way.

thanks for the other replies