Invoking the compiler

Different forms of the XL C/C++ compiler invocation commands support various levels of the C and C++ languages. In most cases, you should use the xlc command to compile your C source files, and the xlc++ command to compile C++ source files. Use xlc++ to link if you have both C and C++ object files.

You can use other forms of the command if your particular environment requires it. Table 1 lists the different basic commands, with the special versions of each basic command. Special commands are described in Table 2.

Note: For each invocation command, the compiler configuration file defines default option settings and, in some cases, macros; for information about the defaults implied by a particular invocation, see the /opt/ibmcmp/vac/11.1/etc/vac.cfg.$OSRelease.gcc$gccVersion file for your system. For example, /opt/ibmcmp/vac/11.1/etc/vac.cfg.sles11.gcc432 or /opt/ibmcmp/vac/11.1/etc/vac.cfg.rhel5.5.gcc412.
Table 1. Compiler invocations
Basic invocations Description Equivalent special invocations
xlc Invokes the compiler for C source files. This command supports all of the ISO C99 standard features, and most IBM language extensions. This invocation is recommended for all applications. xlc_r
c99 Invokes the compiler for C source files. This command supports all ISO C99 language features, but does not support IBM language extensions. Use this invocation for strict conformance to the C99 standard. c99_r
c89 Invokes the compiler for C source files. This command supports all ANSI C89 language features, but does not support IBM language extensions. Use this invocation for strict conformance to the C89 standard. c89_r
cc Invokes the compiler for C source files. This command supports pre-ANSI C, and many common language extensions. You can use this command to compile legacy code that does not conform to standard C. cc_r
gxlc Invokes the compiler for C source files. This command accepts many common GNU C options, maps them to their XL C option equivalents, and then invokes xlc. For more information, refer to Reusing GNU C/C++ compiler options with gxlc and gxlc++.  
xlc++, xlC Invokes the compiler for C++ source files. If any of your source files are C++, you must use this invocation to link with the correct runtime libraries.

Files with .c suffixes, assuming you have not used the -+ compiler option, are compiled as C language source code.

xlc++_r, xlC_r
gxlc++, gxlC Invokes the compiler for C++ files. This command accepts many common GNU C/C++ options, maps them to their XL C/C++ option equivalents, and then invokes xlc++. For more information, refer to Reusing GNU C/C++ compiler options with gxlc and gxlc++.  
Table 2. Suffixes for special invocations
_r-suffixed invocations All _r-suffixed invocations allow for threadsafe compilation and you can use them to link the programs that use multi-threading. Use these commands if you want to create threaded applications.