title: I'm reading open source code (C++) and can't figure out why they put enum this way
body: <p>I found enum be defined like this and can't figure it out why they put leading zero there.</p>
  
  <pre><code>enum SquareDelta {
    DELTA_SSW = -021,
    DELTA_SS = -020,
    DELTA_SSE = -017,
    DELTA_SWW = -012,
    DELTA_SW = -011,
    DELTA_S = -010,
    DELTA_SE = -07,
    DELTA_SEE = -06,
    DELTA_W = -01,
    DELTA_ZERO = 0,
    DELTA_E = 01,
    DELTA_NWW = 06,
    DELTA_NW = 07,
    DELTA_N = 010,
    DELTA_NE = 011,
    DELTA_NEE = 012,
    DELTA_NNW = 017,
    DELTA_NN = 020,
    DELTA_NNE = 021
  };
  </code></pre>
  
  <p>I guess this is not just normal int enum but what is it? could it be in hex like number beginning with "0x" ?</p>