Auxiliary C Code ...
TOKEN makeif(tok, exp, thenpart, elsepart)
TOKEN tok, exp, thenpart, elsepart;
{ tok->tokentype = OPERATOR; /* change tok */
tok->whichval = IFOP; /* to if op */
if (elsepart != NULL)
elsepart->link = NULL;
thenpart->link = elsepart;
exp->link = thenpart;
tok->operands = exp;
return tok;
}