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Compiler Operation - Preprocessor Description
DOS:
VMS:
UNIX:
MPW:
Pathname for alto c
Invocation Command
c:\gsp\files\alt.c
gspcpp -ic:\gsp\files source.c
[gsp. files] al
t.
c
gspcpp -i[gsp.files] source.c
/gsp/files/alt.c
gspcpp -i/gsp/files source.c
:gsp :files :alt .c
gspcpp -i :gsp :files source.c
Note that the include filename is enclosed in double quotes. The preprocessor
first searches for alt. c in the current directory, because source. c is in the
current directory. Then, the preprocessor searches the directory named with
the -i option.
3.1.3.2 Environment Variable
DOS:
VMS:
UNIX:
MPW:
An environment variable is a system symbol that you define and assign a string
to. The preprocessor uses an environment variable named C-DIR to name
alternate directories that contain include files. The commands for assigning
the environment variable are:
set
C-DIR=pathname;another pathname ...
assign "pathname;another pathname ... " C-DIR
UNIX:
setenv
C-DIR "pathname;another pathname '"
"
MPW:
set
C-DIR ":pathname;another: pathname ... "
export
C-DIR
The pathnames are directories that contain include files. You can separate
pathnames with a semicolon or with blanks.
In C source, you can use the
#include directive without specifying any path information; instead, you can
specify the path information with C-D I
R.
For example, assume that a file called source. c contains these statements:
#include
<altl.c>
#include
<alt2.c>
The table below lists the complete pathnames for these files and shows how
to invoke the preprocessor; select the row for your operating system.
Pathnames for altl. c and alt2.c
Invocation Command
c:\gsp\files\altl.c
c:\gsys\alt2.c
set
C-DIR=c:\gsys c:\exec\files
gspcpp -ic:\gsp\files source.c
[gsp.files]altl.c
assign
C-DIR " [gsys]
[exec.files]"
[gsys]alt2.c
gspcpp -i[gsp.files] source.c
/gsp/files/altl.c
setenv C_DIR "/gsys /exec/files
/gsys/alt2.c
gspcpp -i\gsp\files source. c
I
:gsp :files :altl .c
set C-DIR
"
:gsys
:files
"
:gsys :alt2 .c
export C_DIR
gspcpp -i:gsp :files source.c
Note that the include filenames are enclosed in angle brackets.
The pre-
processor first searches for these files in the directories named with C-DIR
and finds al t2. c. Then, the preprocessor searches in the directories named
with the -i option and finds altl. c.
3-5
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