title: error: switch quantity not an integer
body: <p>I have researched my issue all over StackOverflow and multi-google links, and I am still confused. I figured the best thing for me is ask... </p>
  
  <p>Im creating a simple command line calculator. Here is my code so far:</p>
  
  <pre><code>const std::string Calculator::SIN("sin");  
  const std::string Calculator::COS("cos");  
  const std::string Calculator::TAN("tan");  
  const std::string Calculator::LOG( "log" );  
  const std::string Calculator::LOG10( "log10" );
  
  void Calculator::set_command( std::string cmd ) {
  
      for(unsigned i = 0; i &lt; cmd.length(); i++)
      {
      cmd[i] = tolower(cmd[i]);
      }
  
      command = cmd;
  }
  
  bool Calculator::is_legal_command() const {
  
      switch(command)
      {
      case TAN:
      case SIN:
      case COS:
      case LOG:
      case LOG10:
          return true;
          break;
      default:
          return false;
          break;
      }
  
  }
  </code></pre>
  
  <p>the error i get is:</p>
  
  <pre><code>Calculator.cpp: In member function 'bool Calculator::is_trig_command() const':  
  Calculator.cpp: error: switch quantity not an integer  
  Calculator.cpp: error: 'Calculator::TAN' cannot appear in a constant-expression  
  Calculator.cpp: error: 'Calculator::SIN' cannot appear in a constant-expression  
  Calculator.cpp: error: 'Calculator::COS' cannot appear in a constant-expression  
  </code></pre>
  
  <p>The mighty internet, it says strings are allowed to be used in switch statements.</p>
  
  <p>Thanks everyone, I appreciate your help.</p>