title: Regexes for integer constants and for binary numbers
body: <p>I have tried 2 questions, could you tell me whether I am right or not?</p>
  <ol>
  <li><p>Regular expression of nonnegative integer constants in C, where numbers beginning with <code>0</code> are octal constants and other numbers are decimal constants.</p>
  <p>I tried <code>0([1-7][0-7]*)?|[1-9][0-9]*</code>, is it right? And what string could I match? Do you think <code>034567</code> will match and <code>000083</code> match?</p>
  </li>
  <li><p>What is a regular expression for binary numbers <strong>x</strong> such that <strong>h<sup>x</sup> + i<sup>x</sup> = j<sup>x</sup></strong>?</p>
  </li>
  </ol>
  <p>I tried <code>(0|1){32}|1|(10))..</code> do you think a string like <code>10</code> will match and <code>11</code> won’t match?</p>
  <p>Please tell me whether I am right or not.</p>