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    <p><em>Apart from that, is there any other drawback that I miss?</em></p> <p>I'm afraid you've misunderstood the nature of endian conversion problems. "Big endian" doesn't mean your fields are laid out in reverse, so that a </p> <pre><code>struct msg1_bigendian { int32 a; int16 b; uint32 c } </code></pre> <p>on a big endian architecture is equivalent to a</p> <pre><code>struct msg1_littleendian { uint32 c; int16 b; int32 a; } </code></pre> <p>on a little endian architecture. Rather, it means that the byte-order <em>within</em> each field is reversed. Let's assume:</p> <pre><code>a = 0x1000000a; b = 0xb; c = 0xc; </code></pre> <p>On a big-endian architecture, this will be laid out as:</p> <pre><code>10 00 00 0a 00 0b 00 00 00 0c </code></pre> <p>The high-order (most significant) byte comes first.</p> <p>On a little-endian machine, this will be laid out as:</p> <pre><code>0a 00 00 10 0b 00 0c 00 00 00 </code></pre> <p>The lowest order byte comes first, the highest order last.</p> <p>Serialize them and overlay the serialized form of the messages on top of each other, and you will discover the incompatibility:</p> <pre><code>10 00 00 0a 00 0b 00 00 00 0c (big endian) 0a 00 00 10 0b 00 0c 00 00 00 (little endian) int32 a int16 b int32 c </code></pre> <p>Note that this isn't simply a case of the fields running in reverse. You proposal would result in a little endian machine mistaking the big endian representation as:</p> <p>a = 0xc000000; b = 0xb00; c = 0xa000010;</p> <p>Certainly not what was transmitted!</p> <p>You really do have to convert every individual field to network byte order and back again, for every field transmitted. </p> <p>UPDATE:</p> <p>Ok, I understand what you are trying to do now. You want to define the struct in reverse, then memcpy from the <em>end</em> of the byte string to the beginning (reverse copy) and reverse the byte order that way. In which case I would say, yes, this is a hack, and yes, it makes your code un-portable, and yes, it isn't worth it. Converting between byte orders is not, in fact, a very expensive operation and it is far easier to deal with than reversing the layout of every structure. </p>
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