title: Declare a bit in C++
body: <p>I write a program with highly memory cost requirement and I want save memory with no performance lost.
  So I want change every variable which has only two situations into bit.</p>
  
  <p>But I can't find bit type in C++ and <code>bitset</code> in STL is always multiples of 4 byte in 32-bit machine.
  Writing a data struct to manage bits will cause performance lost.</p>
  
  <p>Is there any way to declare a bit value just like <code>bit a;</code>?</p>
  
  <p>Thanks everyone. At last the answer I want is:"you can't buy half bytes in C++".</p>