Question

Can someone help with this C++ code. I am trying to compile and I keep running into these 4 errors. 

#include <iostream>
#include <cassert>
#include <string>
using namespace std;
typedef int     fsm_state;
typedef char    fsm_input;
bool is_final_state(fsm_state state)
{
  return (state == 3) ? true : false;
}
fsm_state get_start_state(void)
{
  return 0;
}
fsm_state move(fsm_state state, fsm_input input)
{
  // our alphabet includes only 'a' and 'b'
  if (input != 'a' && input != 'b')
    assert(0);
  switch (state)
  {
    case 0:
      if (input == 'a')
      {
        return 1;
      }
      else if (input == 'b')
      {
        return 0;
      }
      break;
    case 1:
      if (input == 'a')
      {
        return 1;
      }
      else if (input == 'b')
      {
        return 2;
      }
      break;
    case 2:
      if (input == 'a')
      {
        return 1;
      }
      else if (input == 'b')
      {
        return 3;
      }
      break;
    case 3:
      if (input == 'a')
      {
        return 1;
      }
      else if (input == 'b')
      {
        return 0;
      }
      break;
      default:
        assert(0);
  }
}
bool recognize(string str)
{
  if (str == "")
    return false;
  fsm_state state = get_start_state();
  string::const_iterator i = str.begin();
  fsm_input input = *i;
  while (i != str.end())
  {
    state = move(state, *i);
    ++i;
  }
  if (is_final_state(state))
    return true;
  else
    return false;
}
// simple driver for testing
int main(int argc, char** argv)
{
  recognize(argv[1]) ? cout < 1 : cout < 0;
  return 0;
}

Answer 1

Hi, I have fixed all compile time errors.

Please test with your test cases and let me know in case of any issue.

#include <iostream>
#include <cassert>
#include <string>
using namespace std;
typedef int fsm_state;
typedef char fsm_input;
bool is_final_state(fsm_state state)
{
return (state == 3) ? true : false;
}
fsm_state get_start_state(void)
{
return 0;
}
fsm_state move(fsm_state state, fsm_input input)
{
// our alphabet includes only 'a' and 'b'
if (input != 'a' && input != 'b')
assert(0);
switch (state)
{
case 0:
if (input == 'a')
{
return 1;
}
else if (input == 'b')
{
return 0;
}
break;
case 1:
if (input == 'a')
{
return 1;
}
else if (input == 'b')
{
return 2;
}
break;
case 2:
if (input == 'a')
{
return 1;
}
else if (input == 'b')
{
return 3;
}
break;
case 3:
if (input == 'a')
{
return 1;
}
else if (input == 'b')
{
return 0;
}
break;
default:
assert(0);
}
return -1; // Error code
}
bool recognize(string str)
{
if (str == "")
return false;
fsm_state state = get_start_state();
string::const_iterator i = str.begin();
fsm_input input = *i;
while (i != str.end())
{
state = move(state, *i);
++i;
}
if (is_final_state(state))
return true;
else
return false;
}
// simple driver for testing
int main(int argc, char** argv)
{
recognize(argv[1]) ? cout << "1" : cout << "0";
cout<<endl;
return 0;
}