title: What's sizeof(size_t) on 32-bit vs the various 64-bit data models?
body: <p>On a 64-bit system, <code>sizeof(unsigned long)</code> depends on the data model implemented by the system, for example, it is 4 bytes on LLP64 (Windows), 8 bytes on LP64 (Linux, etc.).  What's <code>sizeof(size_t)</code> supposed to be?  Does it vary with data model like <code>sizeof(long)</code> does?  If so, how?</p>
  
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  <p>References:</p>
  
  <p><a href="http://en.wikipedia.org/wiki/64-bit#64-bit_data_models" rel="noreferrer" title="64-bit computing, 64-bit data models. On Wikipedia.">64-bit data models on Wikipedia</a></p>