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<h2>8.7 Writing codes fragments which are specific to DJGPP</h2>

<p><em><strong>Q</strong>: I must put a DJGPP-specific code fragment into my program.  What
symbol should I use in the <code>#ifdef</code> directive to make it only visible
under DJGPP?</em>

<br><p>
<p><strong>A</strong>:  Use <code>__DJGPP__</code>, like this:

<pre>    #ifdef __DJGPP__
    ... DJGPP-specific code ...
    #else
    ... not seen under DJGPP ...
    #endif
</pre>

<p><code>__DJGPP__</code> has the value of the DJGPP major revision number, so you
can write code fragments which have different behavior under different
versions of DJGPP:

<pre>    #ifdef __DJGPP__
    #if __DJGPP__ &gt; 2
    .... will work only in DJGPP v3.x and later ...
    #else
    .... get here for DJGPP v2.x ...
    #endif
    #else
    .... get here in DJGPP v1.x or non-DJGPP environment
    #endif
</pre>

<p>If you need to distinguish between minor DJGPP revision numbers, use the
symbol <code>__DJGPP_MINOR__</code>.  For example:

<pre>    #if defined(__DJGPP__) &amp;&amp; __DJGPP__ == 2 &amp;&amp; __DJGPP_MINOR__ == 1
    .... will work only in DJGPP v2.01 ....
    #endif
</pre>

<p>Another DJGPP-specific pre-processor symbol which DJGPP defines is
<code>__GO32__</code>; but it is only provided for compatibility with previous
versions of DJGPP (v1.x) and its use should be discouraged.

<p><hr>
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