title: comparison between signed and unsigned integer expressions?
body: <p>currently compiling my set.cpp file(we had to make that file based on the set.h file and test_set.cpp) Using a g++ compiler, and I keep running into these warnings:</p>
  
  <pre><code>set.cpp: In member function âvoid set::remove(const set::value_type&amp;)â:
  set.cpp:30: warning: comparison between signed and unsigned integer expressions
  set.cpp: In member function âbool set::contains(const set::value_type&amp;) constâ:
  set.cpp:50: warning: comparison between signed and unsigned integer expressions
  set.cpp: In function âset set_union(const set&amp;, const set&amp;)â:
  set.cpp:65: warning: comparison between signed and unsigned integer expressions
  set.cpp: In function âset set_intersection(const set&amp;, const set&amp;)â:
  set.cpp:76: warning: comparison between signed and unsigned integer expressions
  set.cpp: In function âset set_difference(const set&amp;, const set&amp;)â:
  set.cpp:90: warning: comparison between signed and unsigned integer expressions
  set.cpp: In function âbool is_subset(const set&amp;, const set&amp;)â:
  set.cpp:104: warning: comparison between signed and unsigned integer expressions
  set.cpp: In function âbool operator==(const set&amp;, const set&amp;)â:
  set.cpp:118: warning: comparison between signed and unsigned integer expressions
      set.cpp: In function âstd::ostream&amp; operator&lt;&lt;(std::ostream&amp;, const set&amp;)â:
  set.cpp:131: warning: comparison between signed and unsigned integer expressions
  </code></pre>
  
  <p>I am unsure of what these mean, and was wondering how one would go about fixing this. </p>