#define GEVHDRSZ ( offsetof(GistEntryVector, vector[0]) ) explanation please - Mailing list pgsql-hackers

From jorge alberto
Subject #define GEVHDRSZ ( offsetof(GistEntryVector, vector[0]) ) explanation please
Date
Msg-id 7e7297630612080853o65132d32ibf46c12e2a8e7967@mail.gmail.com
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Responses Re: #define GEVHDRSZ ( offsetof(GistEntryVector, vector[0]) ) explanation please  (Martijn van Oosterhout <kleptog@svana.org>)
List pgsql-hackers
hi!<br />Can you tell me what does this line means<br />#define GEVHDRSZ    ( offsetof(GistEntryVector, vector[0]) )<br
/><pre><spanclass="preprocessor">#ifndef offsetof</span>
 
<a name="l00501"></a><span class="preprocessor"></span><span class="preprocessor">#define offsetof(type, field)
((long)&((type *)0)->field)</span><br /><span class="preprocessor"></span><span class="preprocessor">
 
#endif   </span><span class="comment">/* offsetof */</span><br /><br /></pre>regards <br />jorge<br /><br />

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