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Annotation of coherent/a/usr/man/ALL/_23include, revision 1.1.1.1

1.1       root        1: 
                      2: 
                      3: #include             Preprocessing Directive             #include
                      4: 
                      5: 
                      6: 
                      7: 
                      8: Read another file and include it
                      9: 
                     10: #iinncclluuddee <_f_i_l_e>
                     11: #iinncclluuddee "_f_i_l_e"
                     12: 
                     13: The  preprocessing directive #include  tells the  preprocessor to
                     14: replace the directive with the contents of file.
                     15: 
                     16: The directive can  take one of two forms: either  the name of the
                     17: file  is enclosed  within angle brackets  (<_h_e_a_d_e_r.hh>), or  it is
                     18: enclosed  within quotation  marks  ("_h_e_a_d_e_r.hh").  Angle  brackets
                     19: tell cpp to look for _f_i_l_e.hh in the directories  named with the -II
                     20: options to the cc command line,  and then in the  standard direc-
                     21: tory.  Quotation marks tell cpp  to look for _f_i_l_e.hh in the source
                     22: file's directory, then in directories named with the  -II options,
                     23: and then in the standard directory.
                     24: 
                     25: Most often, the file being included  is a header, which is a file
                     26: that contains  function prototypes, macro  definitions, and other
                     27: useful material;  as its name  implies, it most  often appears at
                     28: the  head of  a program.   The header  name must  be a  string of
                     29: characters, possibly  followed by a period `.'  and a single let-
                     30: ter, usually (but not always) `h'.   A header name may have up to
                     31: 12 characters  to the left of  the period, and names  may be case
                     32: sensitive.
                     33: 
                     34: #include  directives may  be nested  up to  at least  eight deep.
                     35: That is to say, a file  included by an #include directive may use
                     36: an #include  directive to include  a third file;  that third file
                     37: may also  use a #include directive to include  a fourth file; and
                     38: so on, up to at least eight files.
                     39: 
                     40: Note, too,  that a subordinate header file  is sought relative to
                     41: the original source file, rather than relative to the header that
                     42: calls it  directly.  For example,  suppose that a  file example.c
                     43: resides  in  directory /v/fred/src.   If  example.c contains  the
                     44: directive #include  <header1.h>.  The operating  system will look
                     45: for  header1.h  in  the  standard  directory,  /usr/include.   If
                     46: header1.h  includes the  directive  #include <../header2.h>  then
                     47: COHERENT looks for header2.h not in directory /uussrr, but in direc-
                     48: tory /v/fred.
                     49: 
                     50: A  #include directive  may also  take  the form  #iinncclluuddee _s_t_r_i_n_g,
                     51: where string is a macro that expands into either of the two forms
                     52: described above.
                     53: 
                     54: ***** See Also *****
                     55: 
                     56: header files, C preprocessor
                     57: 
                     58: 
                     59: 
                     60: 
                     61: 
                     62: 
                     63: 
                     64: COHERENT Lexicon                                           Page 1
                     65: 
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