Using the this Pointer to Enable Cascaded Function Calls - C++ Class

C++ examples for Class:this

  1. HOME
  2. C++
  3. Class
  4. this

Description

Using the this Pointer to Enable Cascaded Function Calls

Demo Code

class Time /*  w  ww  .  java  2  s .co m*/
{ 
public: 
    Time( int = 0, int = 0, int = 0 ); // default constructor 

    // set functions (the Time & return types enable cascading) 
    Time &setTime( int, int, int ); // set hour, minute, second 
    Time &setHour( int ); // set hour 
    Time &setMinute( int ); // set minute 
    Time &setSecond( int ); // set second 

    // get functions (normally declared const) 
    int getHour() const; // return hour 
    int getMinute() const; // return minute 
    int getSecond() const; // return second 

    // print functions (normally declared const) 
    void printUniversal() const; // print universal time 
    void printStandard() const; // print standard time 
private: 
    int hour; // 0 - 23 (24-hour clock format) 
    int minute; // 0 - 59 
   int second; // 0 - 59 
}; // end class Time 


#include <iostream> 
#include <iomanip> 
using namespace std; 

Time ::Time( int hr, int min, int sec ) 
{ 
   setTime( hr, min, sec ); 
}

// set values of hour, minute, and second 
Time &Time::setTime( int h, int m, int s ) // note Time & return 
{ 
   setHour( h ); 
   setMinute( m ); 
   setSecond( s ); 
   return *this; // enables cascading 
}

// set hour value 
Time &Time::setHour( int h ) // note Time & return 
{ 
   if ( h >= 0 && h < 24 ) 
       hour = h; 
   else 
       throw invalid_argument( "hour must be 0-23" ); 

   return *this; // enables cascading 
}

// set minute value 
Time &Time::setMinute( int m ) // note Time & return 
{ 
   if ( m >= 0 && m < 60 ) 
       minute = m; 
   else 
       throw invalid_argument( "minute must be 0-59" ); 

    return *this; // enables cascading 
}

// set second value 
Time &Time::setSecond( int s ) // note Time & return 
{ 
    if ( s >= 0 && s < 60 ) 
       second = s; 
   else 
       throw invalid_argument( "second must be 0-59" ); 

    return *this; // enables cascading 
}

// get hour value 
int Time ::getHour() const 
{ 
    return hour; 
}

// get minute value 
int Time ::getMinute() const 
{ 
    return minute; 
}

// get second value 
int Time ::getSecond() const 
{ 
    return second; 
}

// print Time in universal-time format (HH:MM:SS) 
void Time::printUniversal() const 
{ 
    cout << setfill( '0' ) << setw( 2 ) << hour << ":" 
       << setw( 2 ) << minute << ":" << setw( 2 ) << second; 
}

// print Time in standard-time format (HH:MM:SS AM or PM) 
void Time::printStandard() const 
{ 
    cout << ( ( hour == 0 || hour == 12 ) ? 12 : hour % 12 ) 
       << ":" << setfill( '0' ) << setw( 2 ) << minute 
       << ":" << setw( 2 ) << second << ( hour < 12 ? " AM" : " PM" ); 
}

#include <iostream> 
using namespace std; 

int main() 
{ 
    Time t; // create Time object 

    // cascaded function calls 
    t.setHour( 18 ).setMinute( 30 ).setSecond( 22 ); 

    // output time in universal and standard formats 
    cout << "Universal time: "; 
    t.printUniversal(); 

    cout << "\nStandard time: "; 
    t.printStandard(); 

    cout << "\n\nNew standard time: "; 

    // cascaded function calls 
    t.setTime( 20, 20, 20 ).printStandard(); 
    cout << endl; 
}

Result


Related Tutorials