Task: the user enters commands, the program executes them. Wanted to use switch , but he doesn’t want to handle a variable like string , only int .

Here is some of the code:

while (command == "NULL")
{
  cout & lt; & lt; '& gt;';
  cin & gt; & gt; command;
}
if (command == "exit")
{
  exit = 1;
}
if (command == "map")
{
  view_map (map, POLE);
}
if (command == "goto")
{
  string direction;
  int steps;
  cin & gt; & gt; direction & gt; & gt; steps;
  if (steps & lt; 0)
    cout & lt; & lt; "And what about yours?" & lt; & lt; endl;
  if (direction == "left")
    HeroCoord_x = HeroCoord_x - steps;
  if (direction == "right")
    HeroCoord_x = HeroCoord_x + steps;
  if (direction == "up")
    HeroCoord_y = HeroCoord_y - steps;
  if (direction == "down")
    HeroCoord_y = HeroCoord_y + steps;
  if ((HeroCoord_x & lt; 0) || (HeroCoord_x & gt; POLE) || (HeroCoord_y & lt; 0) || (HeroCoord_y & gt; POLE))
  {
    cout & lt; & lt; "Nipalusaitsanah!" & lt; & lt; endl;
    if (direction == "left")
      HeroCoord_x = HeroCoord_x + steps;
    if (direction == "right")
      HeroCoord_x = HeroCoord_x - steps;
    if (direction == "up")
      HeroCoord_y = HeroCoord_y + steps;
    if (direction == "down")
      HeroCoord_y = HeroCoord_y - steps;
  }
  else
  {
    make_map (map, POLE);
    go_to (map, HeroCoord_x, HeroCoord_y);
  }
}

Answer 1, authority 100%

You can make handler mapping and use it.
Something like:

struct Handler {
  void handle () = 0;
  virtual ~ Handler () {}
};
struct ExitHandler: public Handler {
  void handle () {
    // code here
  }
};
struct MapHandler: public Handler {
  void handle () {
    // code here
  }
};
struct GotoHandler: public Handler {
  void handle () {
    // code here
  }
};
// =====================
std :: map & lt; std :: string, Handler * & gt; handlers;
handlers ["exit"] = new ExitHandler ();
handlers ["goto"] = new GotoHandler ();
handlers ["map"] = new MapHandler ();
// -----------------------
while (command == "NULL")
{
  cout & lt; & lt; '& gt;';
  cin & gt; & gt; command;
}
handlers [command] - & gt; handle ();

Answer 2, authority 93%

String-to-number mapping can be used:

std :: map & lt; std :: string, int & gt; mapping;
mapping ["left"] = LEFT;
mapping ["up"] = UP;
mapping ["right"] = RIGHT;
mapping ["down"] = DOWN;
switch (mapping [command]) {
  case LEFT: doLeft (); break;
  case UP: doUp (); break;
  case RIGHT: doRight (); break;
  case DOWN: doDown (); break;
}

Answer 3, authority 100%

If you are not afraid of collisions, then you can use constexpr functions from C++ 11, and do switch by hashes of strings.

// FNV-1a hash, 32-bit
inline constexpr std :: uint32_t fnv1a (const char * str, std :: uint32_t hash = 2166136261UL) {
  return * str? fnv1a (str + 1, (hash ^ * str) * 16777619ULL): hash;
}
int main () {
  std :: string s = "bb";
  switch (fnv1a (s.c_str ())) {
  case fnv1a ("a"): std :: cout & lt; & lt; "A \ n"; break;
  case fnv1a ("bb"): std :: cout & lt; & lt; "B \ n"; break;
  case fnv1a ("ccc"): std :: cout & lt; & lt; "C \ n"; break;
  };
}

Answer 4

1. command == “map” – does it work? Interesting to know how. You are comparing pointers, but you need to compare strings, for this there is the strcmp function (or can the == operator be overloaded for char * by default? I am something off topic 🙂

2. When I was solving a similar problem, I simply wrote a function and put the lines into an array:

   const char * protoCommands [] = {
          "AUTH",
          "REG",
          "ADDPT",
          "ACCPT",
          "GETPTS",
          "GETSTATE",
          "DISC"
         };
         const int protoSize = sizeof (protoCommands) / sizeof (char *);
         / * ... * /
       int switchFunc (char * buf)
       {
        for (int i = 0; i & lt; protoSize; ++ i)
        if (! strcmp (buf, protoCommands [i]))
         return i;
        return -1;
       }
       / * ... * /
       switch (switchFunc (buf))
       {
         ...
       }