DaniWeb Forum Index > Software Development > C++

C++ RSS

C++ Inheritance problem with some syntax errors

Please support our C++ advertiser: Intel Parallel Studio Home

•

Join Date: Feb 2009

Posts: 18

Reputation: danielle23 is an unknown quantity at this point

Solved Threads: 0

danielle23 danielle23 is offline

Offline

Newbie Poster

C++ Inheritance problem with some syntax errors

Mar 30th, 2009

I am working on a code focusing on Inheritance in C++. I am getting some errors regarding the lines that read:
void bat :: double travel_time (double distance, terrain_type t) (lines 56, 68, 113, 125 in animal.h file)
The others that begin with void penguin, mammal, and bird have the same error. The errors read:
--expected unqualified-id before "double"
--expected init declarator before "double"
--expected ',' or ';' before "double"

These seem like simple errors...but it's driving me nuts, I can't seem to find what is wrong. I'm hoping that maybe some fresh eyes could find it? It's also possible I could have something completely wrong in there all together...

Below I have information on what needs to be accomplished in the program. The cpp file and the .h file. Hope this is enough info.

animal class is the base. animal is inherited by mammal and bird. mammal is inherited by cow and bat. bird is inherited by hawk and penguin.
Derived classes from mammal uses travel_time function unless it is overrode (by bat). Derived classes from bird will use the travel_time function unless overrode (by penquin).

There is a chart where the numbers come from in the calculations in the void functions. The math isn't my problem. I think it's the declarators themselves. The problem is in the animal.h file. I just pasted the cpp file for reference to where things will go once program is ran.

I appreciate any input or advice.

cpp file

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <cstdlib>
#include <iostream>
 
using namespace std;
 
#include "animal.h"
 
char menu ();
 
int main(int argc, char *argv[])
{
    animal* the_animal;   // pointer to animal of a type selected by the user
    double distance;
    char animal;
    char command;
    double hours;
    terrain_type terrain;
    int terrain_number;
 
    // pick a default animal
    the_animal = new cow ();
 
    command = menu ();
    // continue executing until user enters a q to quit
        while (command != 'q')
    {
          // select appropriate directory operation based on command
          switch (command)
          {
             case 'a' : cout << "\nChoose an animal: ";
                        cout << "\nh : hawk";
                        cout << "\np : penguin";
                        cout << "\nc : cow";
                        cout << "\nb : bat";
                        cout << "\n\nChoice: ";
                        cin >> animal;
                        // create the selected animal. Return old animal object
                        // to free memory
                        switch (animal)
                        {
                               case 'h' : delete the_animal;
                                          the_animal = new hawk ();
                                          break;
                               case 'p' : delete the_animal;
                                          the_animal = new penguin ();
                                          break;
                               case 'c' : delete the_animal;
                                          the_animal = new cow ();
                                          break;
                               case 'b' : delete the_animal;
                                          the_animal = new bat ();
                                          break;
                               default: cout << "\nIllegal choice, no animal set!";
                        }
                        break;
             case 'p' : cout << "\nCurrent animal is:";
                        // print animal with public method
                        the_animal -> print ();
                        break;
             case 't' : cout << "\nEnter the distance: ";
                        cin >> distance;
                        cout << "Enter the terrain (0:PLAIN, 1:HILL, 2:MOUNTAIN): ";
                        cin >> terrain_number;
                        // change from integer input to terrain type
                        terrain = (terrain_type) terrain_number;
                        // compute travel time with public method
                        hours = the_animal -> travel_time (distance, terrain);
                        cout << "\nThe trip would take " << hours << " hours!";
                        break;
             default: cout << "\nlegal command entered!";
          } // switch
          command = menu ();
    } // while
 
    system("PAUSE");
    return EXIT_SUCCESS;
}
 
// prints the menu and returns user entered character command
char menu ()
{
     char ch;
 
     cout << "\n\n     Animal Menu";
     cout << "\n\na: choose an animal";
     cout << "\np: print current animal";
     cout << "\nt: execute a trip";
     cout << "\nq: quit from the program";
     cout << "\n\nEnter command: ";
     cin >> ch;
     return ch;
}
#include <cstdlib>
#include <iostream>

using namespace std;

#include "animal.h"

char menu ();

int main(int argc, char *argv[])
{
    animal* the_animal;   // pointer to animal of a type selected by the user
    double distance;
    char animal;
    char command;
    double hours;
    terrain_type terrain;
    int terrain_number;
    
    // pick a default animal
    the_animal = new cow ();
    
    command = menu ();
    // continue executing until user enters a q to quit
        while (command != 'q')
    {
          // select appropriate directory operation based on command
          switch (command)
          {
             case 'a' : cout << "\nChoose an animal: ";
                        cout << "\nh : hawk";
                        cout << "\np : penguin";
                        cout << "\nc : cow";
                        cout << "\nb : bat";
                        cout << "\n\nChoice: ";
                        cin >> animal;
                        // create the selected animal. Return old animal object
                        // to free memory
                        switch (animal)
                        {
                               case 'h' : delete the_animal;
                                          the_animal = new hawk ();
                                          break;
                               case 'p' : delete the_animal;
                                          the_animal = new penguin ();
                                          break;
                               case 'c' : delete the_animal;
                                          the_animal = new cow ();
                                          break;
                               case 'b' : delete the_animal;
                                          the_animal = new bat ();
                                          break;
                               default: cout << "\nIllegal choice, no animal set!";
                        }
                        break;
             case 'p' : cout << "\nCurrent animal is:";
                        // print animal with public method
                        the_animal -> print ();
                        break;
             case 't' : cout << "\nEnter the distance: ";
                        cin >> distance;
                        cout << "Enter the terrain (0:PLAIN, 1:HILL, 2:MOUNTAIN): ";
                        cin >> terrain_number;
                        // change from integer input to terrain type
                        terrain = (terrain_type) terrain_number;
                        // compute travel time with public method
                        hours = the_animal -> travel_time (distance, terrain);
                        cout << "\nThe trip would take " << hours << " hours!";
                        break;
             default: cout << "\nlegal command entered!";
          } // switch
          command = menu ();
    } // while
    
    system("PAUSE");
    return EXIT_SUCCESS;
}

// prints the menu and returns user entered character command
char menu ()
{
     char ch;
     
     cout << "\n\n     Animal Menu";
     cout << "\n\na: choose an animal";
     cout << "\np: print current animal";
     cout << "\nt: execute a trip";
     cout << "\nq: quit from the program";
     cout << "\n\nEnter command: ";
     cin >> ch;
     return ch;
}

animal.h

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
enum terrain_type {PLAIN, HILL, MOUNTAIN};
 
// animal class
class animal 
{
      protected:
         char* kind;       // name of animal
         double airspeed;  // speed for animal flying
         double landspeed; // speed for animal walking
      public:
         void print ();    // prints animal data
         // virtual function to compute travel time given a distance and
         // terrain type. Not defined in animal but in derived classes.
         virtual double travel_time (double distance, terrain_type t) = 0;
};
 
// prints an animal's data (inherited by derived classes)
void animal::print ()
{
     cout << "\n\nKind:       " << kind;
     cout << "\nAir Speed:  " << airspeed;
     cout << "\nLand Speed: " << landspeed;
}
 
class mammal : public animal
{
     public:    
        double travel_time (double distance, terrain_type t);
};
class cow : public mammal
{
      public:
      cow();
};
//constructor sets a default animal type, cow
cow :: cow ()
{
    kind = "Cow";
    airspeed = 0;
    landspeed = 3;
}
class bat : public mammal
{
      public:
        bat();
        double travel_time (double distance, terrain_type t);
};
 
bat :: bat ()
{
    kind = "Bat";
    airspeed = 15;
    landspeed = 1;
}
 
void bat :: double travel_time (double distance, terrain_type t)
{
     switch (t)
      {
            case PLAIN: travel_time = (distance/airspeed)
                        break;
            case HILL:  travel_time = (distance/airspeed)
                        break;
            case MOUNTAIN: travel_time = (distance/airspeed)
     }
}
 
void mammal :: double travel_time (double distance, terrain_type t)
{
     switch (t)
      {
            case PLAIN: travel_time = ((distance/landspeed)*1)
                        break;
            case HILL:  travel_time = ((distance/landspeed)*2)
                       break;
            case MOUNTAIN: travel_time = ((distance/landspeed)*3)
     }
}
 
class bird : public animal
{
      public:
        double travel_time (double distance, terrain_type t);    
};
 
class hawk : public bird
{
      public:
         hawk();
};
 
hawk :: hawk ()
{
     kind = "Hawk";
     airspeed = 30;
     landspeed = 4;
}
class penguin : public bird
{
      public:
         penguin();
         double travel_time (double distance, terrain_type t);
 
};
 
penguin :: penguin ()
{
     kind = "Penguin";
     airspeed = 0;
     landspeed = 2;
}
 
void penguin :: double travel_time (double distance, terrain_type t)
{
     switch (t)
      {
            case PLAIN: travel_time = ((distance/landspeed)*1)
                        break;
            case HILL:  travel_time = ((distance/landspeed)*2)
                       break;
            case MOUNTAIN: travel_time = ((distance/landspeed)*3)
     }
}
 
void bird :: double travel_time (double distance, terrain_type t)
{
     switch (t)
      {
            case PLAIN: travel_time = ((distance/landspeed)*1)
                        break;
            case HILL:  travel_time = ((distance/landspeed)*2)
                       break;
            case MOUNTAIN: travel_time = ((distance/landspeed)*3)
     }
}
enum terrain_type {PLAIN, HILL, MOUNTAIN};

// animal class
class animal 
{
      protected:
         char* kind;       // name of animal
         double airspeed;  // speed for animal flying
         double landspeed; // speed for animal walking
      public:
         void print ();    // prints animal data
         // virtual function to compute travel time given a distance and
         // terrain type. Not defined in animal but in derived classes.
         virtual double travel_time (double distance, terrain_type t) = 0;
};

// prints an animal's data (inherited by derived classes)
void animal::print ()
{
     cout << "\n\nKind:       " << kind;
     cout << "\nAir Speed:  " << airspeed;
     cout << "\nLand Speed: " << landspeed;
}

class mammal : public animal
{
     public:    
        double travel_time (double distance, terrain_type t);
};
class cow : public mammal
{
      public:
      cow();
};
//constructor sets a default animal type, cow
cow :: cow ()
{
    kind = "Cow";
    airspeed = 0;
    landspeed = 3;
}
class bat : public mammal
{
      public:
        bat();
        double travel_time (double distance, terrain_type t);
};

bat :: bat ()
{
    kind = "Bat";
    airspeed = 15;
    landspeed = 1;
}

void bat :: double travel_time (double distance, terrain_type t)
{
     switch (t)
      {
            case PLAIN: travel_time = (distance/airspeed)
                        break;
            case HILL:  travel_time = (distance/airspeed)
                        break;
            case MOUNTAIN: travel_time = (distance/airspeed)
     }
}

void mammal :: double travel_time (double distance, terrain_type t)
{
     switch (t)
      {
            case PLAIN: travel_time = ((distance/landspeed)*1)
                        break;
            case HILL:  travel_time = ((distance/landspeed)*2)
                       break;
            case MOUNTAIN: travel_time = ((distance/landspeed)*3)
     }
}

class bird : public animal
{
      public:
        double travel_time (double distance, terrain_type t);    
};

class hawk : public bird
{
      public:
         hawk();
};

hawk :: hawk ()
{
     kind = "Hawk";
     airspeed = 30;
     landspeed = 4;
}
class penguin : public bird
{
      public:
         penguin();
         double travel_time (double distance, terrain_type t);
         
};

penguin :: penguin ()
{
     kind = "Penguin";
     airspeed = 0;
     landspeed = 2;
}

void penguin :: double travel_time (double distance, terrain_type t)
{
     switch (t)
      {
            case PLAIN: travel_time = ((distance/landspeed)*1)
                        break;
            case HILL:  travel_time = ((distance/landspeed)*2)
                       break;
            case MOUNTAIN: travel_time = ((distance/landspeed)*3)
     }
}

void bird :: double travel_time (double distance, terrain_type t)
{
     switch (t)
      {
            case PLAIN: travel_time = ((distance/landspeed)*1)
                        break;
            case HILL:  travel_time = ((distance/landspeed)*2)
                       break;
            case MOUNTAIN: travel_time = ((distance/landspeed)*3)
     }
}

•

Join Date: Aug 2005

Posts: 15,401

Reputation: Ancient Dragon has a reputation beyond repute

Solved Threads: 1467

Ancient Dragon Ancient Dragon is offline

Offline

Still Learning

Re: C++ Inheritance problem with some syntax errors

Mar 30th, 2009

did you try this: double bat::travel_time (double distance, terrain_type t)

Don't PM me with questions -- you might get a nasty PM in response. If you have a question then post it in one of the forums.

•

Join Date: Feb 2009

Posts: 18

Reputation: danielle23 is an unknown quantity at this point

Solved Threads: 0

danielle23 danielle23 is offline

Offline

Newbie Poster

Re: C++ Inheritance problem with some syntax errors

Mar 30th, 2009

No I did not try that, that's exactly what I meant by fresh eyes! Thank you, no more errors on that.

However, now I've run into a new problem. It doesn't like my switch statements. I'm wondering if it would be better to use if statements instead? It's asking for the '&'. It is not call by reference so I can't use that option. Or maybe I'm missing something now in the switch statements that can still allow me to use them...

feel free, anyone, to shoot me any ideas if you have any. Thank you....

•

Join Date: Feb 2009

Posts: 18

Reputation: danielle23 is an unknown quantity at this point

Solved Threads: 0

danielle23 danielle23 is offline

Offline

Newbie Poster

Re: C++ Inheritance problem with some syntax errors

Mar 30th, 2009

If I do in fact use the if statements instead of switch statements, I receive another error:
--expected primary expression before "=="
--expected primary expression before "t"

hmm.

here is what I tried:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
double bat :: travel_time (double distance, terrain_type t)
{
       if (terrain_type t == PLAIN)
       {
         distance = (distance/airspeed);
         }
         if (terrain_type t == HILL)
         {
           distance = (distance/airspeed);
           }
           if (terrain_type t == MOUNTAIN)
           {
             distance = (distance/airspeed);
             }
double bat :: travel_time (double distance, terrain_type t)
{
       if (terrain_type t == PLAIN)
       {
         distance = (distance/airspeed);
         }
         if (terrain_type t == HILL)
         {
           distance = (distance/airspeed);
           }
           if (terrain_type t == MOUNTAIN)
           {
             distance = (distance/airspeed);
             }

•

Join Date: Nov 2007

Posts: 978

Reputation: mitrmkar is just really nice

Solved Threads: 208

mitrmkar

Offline

Posting Shark

Re: C++ Inheritance problem with some syntax errors

Mar 30th, 2009

•

Originally Posted by danielle23

Or maybe I'm missing something now in the switch statements that can still allow me to use them...

Yes, you are missing semicolons ...

Help with Code Tags

(Toggle Plain Text)

void bird :: double travel_time (double distance, terrain_type t)
{
     switch (t)
      {
            case PLAIN: travel_time = ((distance/landspeed)*1) ;
                        break;
            case HILL:  travel_time = ((distance/landspeed)*2) ;
                       break;
            case MOUNTAIN: travel_time = ((distance/landspeed)*3) ;
            // maybe add the final break too
                       break;
     }
}

The if-blocks won't work because you are trying to declare variables of terrain_type and compare them at once, i.e. use

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
double bat :: travel_time (double distance, terrain_type t)
{
       if (t == PLAIN)
       {
         distance = (distance/airspeed);
       }
       // and so on ...
double bat :: travel_time (double distance, terrain_type t)
{
       if (t == PLAIN)
       {
         distance = (distance/airspeed);
       }
       // and so on ...

•

Join Date: Feb 2009

Posts: 18

Reputation: danielle23 is an unknown quantity at this point

Solved Threads: 0

danielle23 danielle23 is offline

Offline

Newbie Poster

Re: C++ Inheritance problem with some syntax errors

Mar 30th, 2009

Great! Thank you, it runs now. I used the if statements instead of the switch statements.

My math is bit weird now, so now I have to find that little error I have in there. All answers come out to be "1.#QNAN" meaning it's obviously not calculating something right. It's not grabbing the data from landspeed and airspeed for some reason. I'm trying to figure that one out now...

•

Join Date: Feb 2009

Posts: 18

Reputation: danielle23 is an unknown quantity at this point

Solved Threads: 0

danielle23 danielle23 is offline

Offline

Newbie Poster

Re: C++ Inheritance problem with some syntax errors

Mar 30th, 2009

Ok, I think I've just about tried everything. I even went back to trying it out with the switch statements, except corrected:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
     switch (t)
      {
            case PLAIN: ((distance/landspeed)*1);
                        break;
            case HILL: ((distance/landspeed)*2);
                       break;
            case MOUNTAIN:((distance/landspeed)*3);
                       break;
     }
     switch (t)
      {
            case PLAIN: ((distance/landspeed)*1);
                        break;
            case HILL: ((distance/landspeed)*2);
                       break;
            case MOUNTAIN:((distance/landspeed)*3);
                       break;
     }

Something in the math somewhere in the problem is not picking up on landspeed and airspeed numbers along with user entered distance. Just keeps giving me the same answer with everything,

Help with Code Tags

C++ Syntax (Toggle Plain Text)

"The trip would take 1.#QNAN hours!"

Any ideas why??

•

Join Date: Aug 2005

Posts: 15,401

Reputation: Ancient Dragon has a reputation beyond repute

Solved Threads: 1467

Ancient Dragon Ancient Dragon is offline

Offline

Still Learning

Re: C++ Inheritance problem with some syntax errors

Mar 31st, 2009

Look at post #5 and compare it with yours. You are missing the part to the left of the = symbol.

Don't PM me with questions -- you might get a nasty PM in response. If you have a question then post it in one of the forums.

•

Join Date: Feb 2009

Posts: 18

Reputation: danielle23 is an unknown quantity at this point

Solved Threads: 0

danielle23 danielle23 is offline

Offline

Newbie Poster

Re: C++ Inheritance problem with some syntax errors

Mar 31st, 2009

I took travel_time off because errors came up asking if I was missing the "&". It's not supposed to be a call by reference, so when I took travel_time out, the program ran and I thought that's how it was supposed to work...until the answer kept coming up as a no number

hmmm....

•

Join Date: Aug 2005

Posts: 15,401

Reputation: Ancient Dragon has a reputation beyond repute

Solved Threads: 1467

Ancient Dragon Ancient Dragon is offline

Offline

Still Learning

Re: C++ Inheritance problem with some syntax errors

#10

Mar 31st, 2009

The post #5 is actually incorrect because it uses travel_time which is the name of the function as if it were a variable name. You need to create another double variable and return it, like this:

Help with Code Tags

(Toggle Plain Text)

double bat::travel_time (double distance, terrain_type t)
{
     double result = 0.0;
     switch (t)
      {
            case PLAIN: result = (distance/airspeed);
                        break;
            case HILL:  result = (distance/airspeed);
                        break;
            case MOUNTAIN: result = (distance/airspeed);
                        break;
                      
     }
     return result;
}

Last edited by Ancient Dragon; Mar 31st, 2009 at 1:33 am.

Don't PM me with questions -- you might get a nasty PM in response. If you have a question then post it in one of the forums.