1CPP(1) BSD General Commands Manual CPP(1)
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4 cpp — C preprocessor
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7 cpp [-ACEMPtVv] [-D macro[=value]] [-d flags] [-I path] [-i file]
8 [-S path] [-U macro] [infile | -] [outfile]
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11 The cpp utility is a macro preprocessor used by the pcc(1) compiler. It
12 is mainly used to include header files, expand macro definitions, discard
13 comments, and perform conditional compilation. cpp is written to comply
14 with the ISO/IEC 9899:1999 (“ISO C99”) specification.
15 The infile input file is optional. If not provided or the file name is
17 "-" (dash), cpp reads its initial file from standard input. The outfile
18 output file is also optional, with output written to standard output if
19 not provided.
20 The options are as follows:
22 -A For assembler-with-cpp input: treat non-directive lines starting
24 with a # as comments.
25 -C Do not discard comments.
27 -D macro[=value]
29 Create a macro definition before processing any input, as if a
30 #define macro value
32 directive had appeared in the source. If value is not set on the
34 command-line, then a value of 1 is used.
35 -d flags
37 Modify output according to flags, which can be a list of charac‐
38 ter flags. The following flags are currently supported:
39 M Do not process any input, but output a list of “#define”
41 statements for all defined macros other than builtin macros
42 (see below).
43 any unknown flags are ignored.
45 -E Modify the exit code, if there were any warnings.
47 -I path
49 Add path to the list of directories searched by the “#include”
50 directive. This may be used to override system include directo‐
51 ries (see -S option). -I may be specified multiple times and is
52 cumulative.
53 -i file
55 Include a file before processing any input, as if a
56 #include "file"
58 directive had appeared in the source. -i may be specified multi‐
60 ple times to include several files.
61 -M Instead of producing a processed C code file, output a list of
63 dependencies for make(1), detailing the files that need to be
64 processed when compiling the input.
65 -P Inhibit generation of line markers. This is sometimes useful
67 when running the preprocessor on something other than C code.
68 -S path
70 Add path to the list of system directories searched by the
71 “#include” directive. The -S option may be specified multiple
72 times and is cumulative.
73 -t Traditional cpp syntax. Do not define the __TIME__, __DATE__,
75 __STDC__, and __STDC_VERSION__ macros.
76 -U macro
78 Undefine a macro before processing any input, as if a
79 #undef macro
81 directive had appeared in the source.
83 -V Verbose debugging output. -V can be repeated for greater detail.
85 (This is only available if the cpp program was built with
86 PCC_DEBUG defined, which is the default).
87 -v Display version.
89 The -D, -i and -U options are processed in the order that they appear on
91 the command line, before any input is read but after the command line
92 options have been scanned.
93 Files referenced by the “#include” directive as "...", are first looked
95 for in the current directory, then as per ⟨...⟩ files, which are first
96 looked for in the list of directories provided by any -I options, then in
97 the list of system directories provided by any -S options. Note that cpp
98 does not define any include directories by default; if no -I or -S
99 options are given, then only the current directory will be searched and
100 no system files will be found.
101 Builtin Macros
103 A few macros are interpreted inside the cpp program:
104 __DATE__ Expands to a quoted string literal containing the date in the
106 form "Mmm dd yyyy", where the names of the months are the same as those
107 generated by the asctime(3) function, and the first character of dd is a
108 space character if the value is less than 10.
109 __FILE__ Expands to a quoted string literal containing the presumed name
111 of the current source file. When reading source from standard input, it
112 expands to "⟨stdin⟩".
113 __LINE__ Expands to an integer constant representing the presumed line
115 number of the source line containing the macro.
116 __STDC__ Expands to the integer constant “1”, meaning that the compiler
118 conforms to ISO/IEC 9899:1990 (“ISO C90”).
119 __STDC_VERSION__ Expands to the integer constant “199901L”, indicating
121 that cpp conforms to ISO/IEC 9899:1999 (“ISO C99”).
122 __TIME__ Expands to a quoted string literal containing the time in the
124 form "hh:mm:ss" as generated by the asctime(3) function.
125 Also see the -t option.
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129 The cpp utility exits with one of the following values:
130 0 Successfully finished.
132 1 An error occurred.
133 2 The -E option was given, and warnings were issued.
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136 as(1), ccom(1), make(1), pcc(1), asctime(3)
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139 The cpp command comes from the original Portable C Compiler by S. C.
140 Johnson, written in the late 70's. The code originates from the V6 pre‐
141 processor with some additions from V7 cpp and ansi/c99 support.
142 A lot of the PCC code was rewritten by Anders Magnusson.
144 This product includes software developed or owned by Caldera Interna‐
146 tional, Inc.
147BSD February 26, 2013 BSD