C / C++ / MFC

#define OPTION_A
//#define OPTION_B -- this is turned off since it is commented out
  
// then later in your code perhaps something like this
    
#ifdef OPTION_A
  // do option A here
#endif
  
#ifdef OPTION_B
  // do option B here
#endif

#define OPTION_A 0
#define OPTION_B 1
  
#define DEFAULT_OPTION OPTION_A
  
int nOption = DEFAULT_OPTION;
  
// then later in your code perhaps something like this
  
switch( nOption )
{
    case OPTION_A:
    {
        // do option A here  
    }
    break;
  
    case OPTION_B:
    {
        // do option B here  
    }
    break;
}

if( "1" == "1" )
{
   ...
   "1" = "0";
}

#define YES 1
#define NO 0
  
int StartYourEngines = YES;
  
if( StartYourEngines == YES )
{
   ...
   StartYourEngines = NO;
}

int StartYourEngines = 1;
  
if( StartYourEngines == 1 )
{
   ...
   StartYourEngines = 0;
}

class MyClass
{
protected:
   BOOL m_bFirstTime;
   
public:
   MyClass()
     : m_bFirstTime( TRUE )
   {
   }
   
   void MyFunction()
   {
      if( m_bFirstTime )
      {
          // do something here only the first time this function is called
   
          m_bFirstTime = FALSE;
      }
   }
};

class MyClass
{
protected:
   BOOL m_bInitialized;
  
public:
   MyClass()
     : m_bInitialized( FALSE )
   {
   }
  
   virtual ~MyClass()
   {
      UnInitialize();
   }
  
   BOOL Initialize()
   {
      BOOL bResult = FALSE;
      {
         // TODO: do whatever initialization is required, and if
         // it succeeds set the following values to indicate it
   
         m_bInitialized = TRUE;
         bResult = TRUE;
      }
      return bResult;
   }
  
   void UnInitialize()
   {
      if( m_bInitialized )
      {
          // TODO: clean up
  
          m_bInitialized = FALSE;
      }
   }
    
   BOOL MyFunction()
   {
       BOOL bResult = FALSE;
       {
          if( m_bInitialized )
          {
             // TODO: do something that required initialization
             // and set bResult to TRUE if it succeeded
   
             bResult = TRUE;
          }
       }
       return bResult;
   }
};

void MyFunction()
{
   static v_bFirstTime = TRUE;
   
   if( v_bFirstTime )
   {
      // do something here only the first time this function is called
   
      v_bFirstTime = FALSE;
   }
}

static g_bFirstTime = TRUE;
   
void MyFunction()
{
   if( g_bFirstTime )
   {
      // do something here only the first time this function is called
   
      g_bFirstTime = FALSE;
   }
}