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copied!<p>If you really need to good performing comparation of integers of arbitrary sizes I recommend you look at <a href="http://gmplib.org/" rel="nofollow">The GNU Multiple Precision Arithmetic Library</a>. That requires you to use it's special mpz_t type (which has the length included). Then you can use the function <code>int mpz_cmp(mpz_t op1, mpz_t op2)</code>. Deciding on your own representation of big integers and implement it in way that is both fairly portable and efficient is not trivial.</p> <p>If, on the other hand, you just need the standard integer sizes you mention I think your implementation is fine. But for even better portability you shouldn't make assumptions on the various integer sizes:</p> <pre><code>#include <stdint.h> int intcmp(const void *a, const void *b, size_t size) { switch (size) { case 1: return (*(int8_t*)a > *(int8_t*)b) - (*(int8_t*)a < *(int8_t*)b) case 2: return (*(int16_t*)a > *(int16_t*)b) - (*(int16_t*)a < *(int16_t*)b) case 4: return (*(int32_t*)a > *(int32_t*)b) - (*(int32_t*)a < *(int32_t*)b) case 8: return (*(int64_t*)a > *(int64_t*)b) - (*(int64_t*)a < *(int64_t*)b) } assert(0); return 0; } </code></pre> <p>Perhaps you'll find it better to create a separate function for each length you need instead of using the same for all? And finally, if efficiency is important, it is often less efficient to do arithmetics with <strong>char</strong> or <strong>short</strong> than with <strong>int</strong>. So try to avoid the cases where you need to call this function with char or short and use int instead.</p>

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