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| <title>The GNU Fortran Compiler: Non-Fortran Main Program</title> |
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| Next: <a href="Naming-and-argument_002dpassing-conventions.html#Naming-and-argument_002dpassing-conventions" accesskey="n" rel="next">Naming and argument-passing conventions</a>, Previous: <a href="GNU-Fortran-Compiler-Directives.html#GNU-Fortran-Compiler-Directives" accesskey="p" rel="prev">GNU Fortran Compiler Directives</a>, Up: <a href="Mixed_002dLanguage-Programming.html#Mixed_002dLanguage-Programming" accesskey="u" rel="up">Mixed-Language Programming</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p> |
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| <a name="Non_002dFortran-Main-Program-1"></a> |
| <h3 class="section">7.3 Non-Fortran Main Program</h3> |
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| <tr><td align="left" valign="top">• <a href="_005fgfortran_005fset_005fargs.html#g_t_005fgfortran_005fset_005fargs" accesskey="1">_gfortran_set_args</a>:</td><td> </td><td align="left" valign="top">Save command-line arguments |
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| |
| <p>Even if you are doing mixed-language programming, it is very |
| likely that you do not need to know or use the information in this |
| section. Since it is about the internal structure of GNU Fortran, |
| it may also change in GCC minor releases. |
| </p> |
| <p>When you compile a <code>PROGRAM</code> with GNU Fortran, a function |
| with the name <code>main</code> (in the symbol table of the object file) |
| is generated, which initializes the libgfortran library and then |
| calls the actual program which uses the name <code>MAIN__</code>, for |
| historic reasons. If you link GNU Fortran compiled procedures |
| to, e.g., a C or C++ program or to a Fortran program compiled by |
| a different compiler, the libgfortran library is not initialized |
| and thus a few intrinsic procedures do not work properly, e.g. |
| those for obtaining the command-line arguments. |
| </p> |
| <p>Therefore, if your <code>PROGRAM</code> is not compiled with |
| GNU Fortran and the GNU Fortran compiled procedures require |
| intrinsics relying on the library initialization, you need to |
| initialize the library yourself. Using the default options, |
| gfortran calls <code>_gfortran_set_args</code> and |
| <code>_gfortran_set_options</code>. The initialization of the former |
| is needed if the called procedures access the command line |
| (and for backtracing); the latter sets some flags based on the |
| standard chosen or to enable backtracing. In typical programs, |
| it is not necessary to call any initialization function. |
| </p> |
| <p>If your <code>PROGRAM</code> is compiled with GNU Fortran, you shall |
| not call any of the following functions. The libgfortran |
| initialization functions are shown in C syntax but using C |
| bindings they are also accessible from Fortran. |
| </p> |
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| Next: <a href="Naming-and-argument_002dpassing-conventions.html#Naming-and-argument_002dpassing-conventions" accesskey="n" rel="next">Naming and argument-passing conventions</a>, Previous: <a href="GNU-Fortran-Compiler-Directives.html#GNU-Fortran-Compiler-Directives" accesskey="p" rel="prev">GNU Fortran Compiler Directives</a>, Up: <a href="Mixed_002dLanguage-Programming.html#Mixed_002dLanguage-Programming" accesskey="u" rel="up">Mixed-Language Programming</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p> |
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