(autocf21.info.gz) Examining Declarations
Info Catalog
(autocf21.info.gz) Writing Tests
(autocf21.info.gz) Writing Tests
(autocf21.info.gz) Examining Syntax
5.1 Examining Declarations
==========================
The macro `AC_TRY_CPP' is used to check whether particular header files
exist. You can check for one at a time, or more than one if you need
several header files to all exist for some purpose.
-- Macro: AC_TRY_CPP (INCLUDES, [ACTION-IF-TRUE [, ACTION-IF-FALSE]])
INCLUDES is C or C++ `#include' statements and declarations, on
which shell variable, backquote, and backslash substitutions are
performed. (Actually, it can be any C program, but other
statements are probably not useful.) If the preprocessor produces
no error messages while processing it, run shell commands
ACTION-IF-TRUE. Otherwise run shell commands ACTION-IF-FALSE.
This macro uses `CPPFLAGS', but not `CFLAGS', because `-g', `-O',
etc. are not valid options to many C preprocessors.
Here is how to find out whether a header file contains a particular
declaration, such as a typedef, a structure, a structure member, or a
function. Use `AC_EGREP_HEADER' instead of running `grep' directly on
the header file; on some systems the symbol might be defined in another
header file that the file you are checking `#include's.
-- Macro: AC_EGREP_HEADER (PATTERN, HEADER-FILE, ACTION-IF-FOUND [,
ACTION-IF-NOT-FOUND])
If the output of running the preprocessor on the system header file
HEADER-FILE matches the `egrep' regular expression PATTERN,
execute shell commands ACTION-IF-FOUND, otherwise execute
ACTION-IF-NOT-FOUND.
To check for C preprocessor symbols, either defined by header files
or predefined by the C preprocessor, use `AC_EGREP_CPP'. Here is an
example of the latter:
AC_EGREP_CPP(yes,
[#ifdef _AIX
yes
#endif
], is_aix=yes, is_aix=no)
-- Macro: AC_EGREP_CPP (PATTERN, PROGRAM, [ACTION-IF-FOUND [,
ACTION-IF-NOT-FOUND]])
PROGRAM is the text of a C or C++ program, on which shell
variable, backquote, and backslash substitutions are performed.
If the output of running the preprocessor on PROGRAM matches the
`egrep' regular expression PATTERN, execute shell commands
ACTION-IF-FOUND, otherwise execute ACTION-IF-NOT-FOUND.
This macro calls `AC_PROG_CPP' or `AC_PROG_CXXCPP' (depending on
which language is current, Language Choice), if it hasn't
been called already.
Info Catalog
(autocf21.info.gz) Writing Tests
(autocf21.info.gz) Writing Tests
(autocf21.info.gz) Examining Syntax
automatically generated byinfo2html