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| <h4 class="subsection">7.1.3 Interoperable Global Variables</h4> |
| |
| <p>Variables can be made accessible from C using the C binding attribute, |
| optionally together with specifying a binding name. Those variables |
| have to be declared in the declaration part of a <code>MODULE</code>, |
| be of interoperable type, and have neither the <code>pointer</code> nor |
| the <code>allocatable</code> attribute. |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample"> MODULE m |
| USE myType_module |
| USE ISO_C_BINDING |
| integer(C_INT), bind(C, name="_MyProject_flags") :: global_flag |
| type(myType), bind(C) :: tp |
| END MODULE |
| </pre></div> |
| |
| <p>Here, <code>_MyProject_flags</code> is the case-sensitive name of the variable |
| as seen from C programs while <code>global_flag</code> is the case-insensitive |
| name as seen from Fortran. If no binding name is specified, as for |
| <var>tp</var>, the C binding name is the (lowercase) Fortran binding name. |
| If a binding name is specified, only a single variable may be after the |
| double colon. Note of warning: You cannot use a global variable to |
| access <var>errno</var> of the C library as the C standard allows it to be |
| a macro. Use the <code>IERRNO</code> intrinsic (GNU extension) instead. |
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