C Language Levels
There are several forms of IBM C and C++ Compilers invocation commands that support various version levels of the C and C++ languages. Normally, you should use the xlc command for compiling your source files. You can, however, use other forms of the command if your particular environment and file systems require it. The various compiler invocations commands are:
Invocation Commands for IBM C and C++ Compilers
xlC xlC128 xlC_r xlC_r4 xlC_r7
xlc xlc128 xlc_r xlc_r4 xlc_r7
cc cc128 cc_r cc_r4 cc_r7
CC_4
c89
The four basic compiler invocation commands appear as the first entry of each line in the table above. Select a basic invocation using the following criteria:
xlC |
Invokes the compiler so that source files are compiled as C++ language
source code. Files with .c suffixes, assuming you have not used the -+ compiler option, are compiled as C language source code with a default language level of ansi, and compiler option -qansialias specified to allow type-based aliasing. Use this invocation for new C and C++ programs. |
xlc |
Invokes the compiler for C or C++ source files with a default language level of ansi, and specifies compiler option -qansialias to allow type-based aliasing. Use this invocation for new C programs. |
cc |
Invokes the compiler for C or C++ source files with a default language level of extended and compler options -qnoro and -qnoroconst (to provide compatibility with the RT compiler and placement of string literals or constant values in read/write storage). Use this invocation for legacy C code that does not require compliance with ANSI C. |
c89 |
Invokes the compiler for C or C++ source files, with a default language
level of ansi, and specifies compiler options -qansialias (to allow type based aliasing)
and -qnolonglong (disabling use of long
long), and sets -D_ANSI_C_SOURCE
(for ANSI-conformant headers). Use this invocation for strict conformance to the ANSI
standard. |
IBM C and C++ Compilers provides variations on the four basic compiler invocations. These variations are described below:
| 128-suffixed Invocations | All 128-suffixed invocation commands are functionally similar to their corresponding base compiler invocations. They specify the -qldbl128 option, which increases the length of long double types in your program from 64 to 128 bits. |
| _r-suffixed Invocations | All _r-suffixed invocations additionally sets the macro
name -D_THREAD_SAFE, and add the
libraries -L/usr/lib/threads, -Lusr/lib/dce,
-lc_r and -lpthreads. Use the -r-suffixed invocations if you want to create either Posix or AIX DCE threaded applications. _r4-suffixed invocations provide compatibility between DCE |
