#iiffddeeff -- Preprocessing Directive

Include code conditionally

The  preprocessing  directive #iiffddeeff  checks  whether  _i_d_e_n_t_i_f_i_e_r has  been
defined as a  macro name.  If _i_d_e_n_t_i_f_i_e_r has been  defined as a macro, then
the preprocessor  includes _g_r_o_u_p within the program, up  to the next #eelliiff,
#eellssee, or  #eennddiiff directive.  If _i_d_e_n_t_i_f_i_e_r has  not been defined, however,
then _g_r_o_u_p is skipped.

An #iiffddeeff directive  can be followed by any number  of #eelliiff directives, by
one #eellssee directive, and must be followed by an #eennddiiff directive.

_E_x_a_m_p_l_e
For an example of using this directive in a program, see aasssseerrtt.

_S_e_e _A_l_s_o
#eelliiff, #eellssee, #eennddiiff, #iiff, #iiffnnddeeff, CC pprreepprroocceessssoorr, ddeeffiinneedd
ANSI Standard, section 6.8.1
