multiline macro with embedded #

[Hal Styli]

Hello, can someone please help with the following attempt at defining a
macro ...

I want to wrap the following in a macro:-

if HEAD is defined then
head=p;
define HEAD
else
tail->next=p;
end
tail=p;

Here is the attemp:-

#define PTRS \
#ifndef HEAD \
head=p; \
#define HEAD 1 \
#else \
tail->next=p; \
#endif \
tail=p;

Predictably this comes out as: #ifndef HEAD head=p; #define HEAD 1 #else
tail->next=p; #endif tail=p;
I don't thisk this is compiler specific but just for the record,
Borland BCC give me .. Illegal character '#' (0x23) in function main

I'm hoping it is possible to accomplish what I want to do with macros.

Thanks in advance for any help given.

Hal.