Can a C macro contain temporary variables?

Question

I have a function that I need to macro\'ize. The function contains temp variables and I can\'t remember if there are any rules about use of temporary variables in macro subs

Answer 1

A not perfect solution: (does not work with recursive macros, for example multiple loops inside each other)

#define JOIN_(X,Y) X##Y
#define JOIN(X,Y) JOIN_(X,Y)
#define TMP JOIN(tmp,__LINE__)

#define switch(x,y) int TMP = x; x=y;y=TMP

int main(){
  int x = 5,y=6;
  switch(x,y);
  switch(x,y);
}

will become after running the preprocessor:

int main(){
   int x=5,y=6;
   int tmp9 = x; x=y; y=tmp9;
   int tmp10 = x; x=y; y=tmp10;
}