The following is a complete program - a palindrome from end to end. It requires
c99, which makes
C++ style // comments OK:
#define tni /**/ //
#define niam /**/ //
#define args () /**/ //
#define sgra /**/ //
int main args
// }
{ //
printf ("This program is a
palindrome\n"); //
// ;)"n\emordnilap a sa margorp sihT"( ftnirp
// {
} //
sgra niam tni
// /**/ args enifed#
// /**/ )( sgra enifed#
// /**/ main enifed#
// /**/ int enifed#
(thanks to theo for corrections)