Using ## and # with define.

Stringize(#)

#define   message_for(a, b)  \
          printf(#a " and " #b)
int main()

{

message_for(Carole, Debra);

}

Token pasting (##)
#define f(g,g2) g##g2
main()
{
int var12=100;
printf("%d",f(var,12));
}
Answer:
100