Data Structures problem

Question

kazek 0 Newbie Poster

16 Years Ago

I've been struggling with this program for few several days now..
It's an implementation of Data structures. I'm trying to use Linked Lists, Sorting and Searching concepts.

#include<iostream>
#include <iomanip>
#include <fstream>
#include <cstdlib>

using namespace std;

class videoShopSystem{
    public: 
         bool empty() const;   
         void displayMainMenu();
         void menuChoice(int key);
         void addNewRecord();
         void displayRecord();
         void editRecord(); //editing
         void deleteRecord();//deleting
         void saveRecord(string filename);//saving
         void loadRecord(string filename);//loading
         void exit();
         
         videoShopSystem():capacity(10), size(0)
         {
             head = tail = cur = prev = -1; //list is empty
             data = new ListNode[capacity];                   
         }
    
    private: 
         class ListNode{
               public:
                   int VideoID;
                   string VideoName;
                   int next;
                   
                   ListNode():VideoID(0), next(-1){}    
          };                
          ListNode *data;
          int size, capacity;
          int head, tail, cur, prev;
        
};

void videoShopSystem::addNewRecord() //implementation of linked list
{
 
     if(size!=capacity)
     {
      if(head == tail) {head = 0; tail = 0;}
      
      cur = tail;
      tail++;
                       
      cout << "Video Record ID: ";
      cin >> data[cur].VideoID;
      cout << "Movie/Video Title: ";
      cin.ignore(1, '\n');
      getline(cin, data[cur].VideoName);
      cout <<endl;
      
      size++;
     }
     else
         cout<< "Capacity reached maximum!!!";
}           

void videoShopSystem::displayRecord()
{
     cout << "Video ID\t\tVideoName" <<endl;
     cout << "------------------------------"<<endl;
     
     for(int i=head; i<size; i++)
     cout << data[i].VideoID <<"\t\t" <<data[i].VideoName<<endl;
      
}
/*
void videoShopSystem::editRecord()
{
     cout << "Enter Record ID: ";
     cin >> data[cur].VideoID;
     



}
*/

void videoShopSystem::saveRecord(string filename)
{
   ofstream fout(filename.c_str());
   if (fout.is_open()) 
    {
     if ( empty() ) 
      {
      cout << "Nothing on List. No Save" << endl;
      system("PAUSE");
      
      }else {
      cur = head;//current is at start
      while (cur != -1)// not at end
      {
        fout << data[cur].VideoID;
        cur = data[cur].next;//loop to next until =-1(end)
      }
    }
  } 
  else 
  {
    cerr << "Can't open file " << filename << endl;//incase of error
    system("PAUSE");
    } 
 fout.close();  
  

}
void videoShopSystem::displayMainMenu()
{
    cout<< "---------------Video Shop System--------------" <<endl;
    //cout<< "-----------------" <<endl;
    cout<< "           1) Add New Record"<<endl;
    cout<< "           2) View All Records"<<endl;
    cout<< "           3) Edit Record"<<endl;
    cout<< "           4) Delete Record"<<endl;
    cout<< "           5) Save Record"<<endl;
    cout<< "           6) Load Record"<<endl;
    cout<< "           7) Quit"<<endl<<endl;
    
    
    cout<< "Enter Choice: ";

}

void videoShopSystem::menuChoice(int key)
{
    switch(key)
    {
               case 1: cout<<"# Add New Record #"<<endl;
                       addNewRecord();
               break;
               case 2: cout<<"# View All Records #"<<endl;
                       displayRecord();
               break;
               case 3: cout<<"# Edit Record #"<<endl;
                       
               break;
               case 4: cout<<"# Delete Record #"<<endl;
               break;
               case 5: cout<<"# Save Record #"<<endl;   
                       saveRecord(string filename);                        
               break;
               case 6: cout<<"# Load Record #"<<endl;
               break;
               case 7: cout<<"Game Over!"<<endl;
               break;
    }
    system("pause");
    system("cls");  
     
}


int main(){
    
    videoShopSystem obj1;
    string filename;
    int key;
    
    do{
    
    obj1.displayMainMenu();
    cin >>key;
    system("cls");
    obj1.menuChoice(key);
    
    }while(key!=7);
    
    
    //system("pause");
    return 0;
}

I'm currently working on the save function which is where I've hit a wall. At this point when I compile I get the following error..

In member function `void videoShopSystem::menuChoice(int)':
147 expected primary-expression before "filename"

What's wrong with my code ?

c++

3 Contributors
11 Replies
175 Views
6 Days Discussion Span
Latest Post 16 Years Ago Latest Post by miepmuts

Nick Evan 4,005 Industrious Poster

16 Years Ago

line 147 calls a function which expects an string as input: saveRecord(string filename); You can't declare a string like that. You could solve the problem in two ways:

Change line 147 to:

saveRecord("c:\\a_file.txt");

or:

string filename = "c:\\a_file.txt");
saveRecord(filename);

Another problem is that you never define the function bool empty() const;

Nick Evan 4,005 Industrious Poster

16 Years Ago

Tried that and I get a linker error..

That shouldn't happen.. Could you post the code that gives you that error?

Nick Evan 4,005 Industrious Poster

16 Years Ago

You forgot to #include <string> Also, you need to define the 'empty' function. Something like:

bool videoShopSystem::empty() const
{
    //do stuff
    return true;
}

And last but not least: "c:\a_file.txt" is not the same as "c:\\a_file.txt" The extra slash is there for a reason. It's called an escape-character

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kazek 0 Newbie Poster · Answer 1 · 2008-09-10T16:32:57+00:00

line 147 calls a function which expects an string as input: saveRecord(string filename); You can't declare a string like that. You could solve the problem in two ways:
Change line 147 to:
saveRecord("c:\\a_file.txt");
or:
string filename = "c:\\a_file.txt");
saveRecord(filename);
Another problem is that you never define the function bool empty() const;

Tried that and I get a linker error..

[Linker error] undefined reference to `videoShopSystem::saveRecord(std::string)'
ld returned 1 exit status

kazek 0 Newbie Poster · Answer 2 · 2008-09-10T17:12:16+00:00

#include<iostream>
#include <iomanip>
#include <fstream>
#include <cstdlib>

using namespace std;

class videoShopSystem{
    public: 
         bool empty() const;   
         void displayMainMenu();
         void menuChoice(int key);
         void addNewRecord();
         void displayRecord();
         void editRecord(); //editing
         void deleteRecord();//deleting
         void saveRecord(string filename);//saving
         void loadRecord(string filename);//loading

         
         videoShopSystem():capacity(10), size(0)
         {
             head = tail = cur = prev = -1; //list is empty
             data = new ListNode[capacity];                   
         }
    
    private: 
         class ListNode{
               public:
                   int VideoID;
                   string VideoName;
                   int next;
                   
                   ListNode():VideoID(0), next(-1){}    
          };                
          ListNode *data;
          int size, capacity;
          int head, tail, cur, prev;
        
};

void videoShopSystem::addNewRecord() //implementation of linked list
{
 
     if(size!=capacity)
     {
      if(head == tail) {head = 0; tail = 0;}
      
      cur = tail;
      tail++;
                       
      cout << "Video Record ID: ";
      cin >> data[cur].VideoID;
      cout << "Movie/Video Title: ";
      cin.ignore(1, '\n');
      getline(cin, data[cur].VideoName);
      cout <<endl;
      
      size++;
     }
     else
         cout<< "Capacity reached maximum!!!";
}           

void videoShopSystem::displayRecord()
{
     cout << "Video ID\t\tVideoName" <<endl;
     cout << "------------------------------"<<endl;
     
     for(int i=head; i<size; i++)
     cout << data[i].VideoID <<"\t\t" <<data[i].VideoName<<endl;
      
}
/*
void videoShopSystem::editRecord()
{
     cout << "Enter Record ID: ";
     cin >> data[cur].VideoID;
     



}
*/

void videoShopSystem::saveRecord(string filename)
{
   ofstream fout(filename.c_str());
   if (fout.is_open()) 
    {
     if ( empty() ) 
      {
      cout << "Nothing on List. No Save" << endl;
      system("PAUSE");
      
      }else {
      cur = head;//current is at start
      while (cur != -1)// not at end
      {
        fout << data[cur].VideoID;
        cur = data[cur].next;//loop to next until =-1(end)
      }
    }
  } 
  else 
  {
    cerr << "Can't open file " << filename << endl;//incase of error
    system("PAUSE");
    } 
 fout.close();  
  

}
void videoShopSystem::displayMainMenu()
{
    cout<< "---------------Video Shop System--------------" <<endl;
    //cout<< "-----------------" <<endl;
    cout<< "           1) Add New Record"<<endl;
    cout<< "           2) View All Records"<<endl;
    cout<< "           3) Edit Record"<<endl;
    cout<< "           4) Delete Record"<<endl;
    cout<< "           5) Save Record"<<endl;
    cout<< "           6) Load Record"<<endl;
    cout<< "           7) Quit"<<endl<<endl;
    
    
    cout<< "Enter Choice: ";

}

void videoShopSystem::menuChoice(int key)
{
    switch(key)
    {
               case 1: cout<<"# Add New Record #"<<endl;
                       addNewRecord();
               break;
               case 2: cout<<"# View All Records #"<<endl;
                       displayRecord();
               break;
               case 3: cout<<"# Edit Record #"<<endl;
                       
               break;
               case 4: cout<<"# Delete Record #"<<endl;
               break;
               case 5: cout<<"# Save Record #"<<endl;   
                       saveRecord("c:\a_file.txt");                       
               break;
               case 6: cout<<"# Load Record #"<<endl;
               break;
               case 7: cout<<"Game Over!"<<endl;
               break;
    }
    system("pause");
    system("cls");  
     
}


int main(){
    
    videoShopSystem obj1;
    string filename;
    int key;
    
    do{
    
    obj1.displayMainMenu();
    cin >>key;
    system("cls");
    obj1.menuChoice(key);
    
    }while(key!=7);
    
    
    //system("pause");
    return 0;
}

That's the code that gives me the linker error

kazek 0 Newbie Poster · Answer 3 · 2008-09-10T17:38:06+00:00

Thanks.. The errors are gone.

But the funny thing is when I save a few records for example..

1 Titanic
2 Star Wars

On opening the file I only see the number "1"

Do you know why that happens ? Then maybe I can work from there.

miepmuts 10 Newbie Poster · Answer 4 · 2008-09-10T18:08:54+00:00

First of all you are only outputting the videoID to the file.

Second: in the displayRecord method you use a for-loop to iterate through all the nodes in the list, but in the saveRecord you use a while-loop.

If the for-loop works, why not re-use that piece of code. Except when outputting to the screen, output to the file.

kazek 0 Newbie Poster · Answer 5 · 2008-09-10T18:20:12+00:00

Nice :) Thanks

One hurdle down...

I'll keep you posted

kazek 0 Newbie Poster · Answer 6 · 2008-09-13T14:15:02+00:00

This is how far I've gone with the Load (from a file) function... Line 188

#include<iostream>
#include <iomanip>
#include <fstream>
#include <cstdlib>
#include <string>

using namespace std;

class videoShopSystem{
    public: 
         bool empty() const;   
         void displayMainMenu();
         void menuChoice(int key);
         void push_back(char ch);
         void addNewRecord();
         void displayRecord();
         void editRecord(); //editing
         void deleteRecord();//deleting
         void saveRecord(string filename);//saving
         void loadRecord(string filename);//loading
         void clear();
         int size1() const;
         
         videoShopSystem():capacity(10), size(0)
         {
             head = tail = cur = prev = -1; //list is empty
             data = new ListNode[capacity];                   
         }
    
    private: 
         int getFirstEmptySlot();
         void increaseCapacity();
             
         class ListNode{
               public:
                   int VideoID;
                   string VideoName;
                   int next;
                   
                   ListNode():VideoID(0), next(-1){}    
          };                
          ListNode *data;
          int size, capacity;
          int head, tail, cur, prev;
        
};

bool videoShopSystem::empty() const //checks if list is empty
{
     if (head == -1) return true;
     return false;
}

void videoShopSystem::clear() // Function to clear list before reading data
{
 size = 0;
 head = tail = cur = prev = -1;

 for (int i=0; i<capacity; i++)
    data[i].VideoID = '\0';
}

int videoShopSystem::size1() const //Size function
{
 return size;
}

void videoShopSystem::push_back(char ch) //push Back
{
 if ( empty() )
  {
   data[0].VideoID = ch;
   data[0].VideoID = -1;
   head = tail = 0;
  } 
  else 
    {
     int slot = getFirstEmptySlot();
     data[slot].VideoID = ch;
     data[slot].next = -1;

     data[tail].next = slot;
     tail = slot;
    }
 size++;    
}

int videoShopSystem::getFirstEmptySlot() //return first empty slot in list
{
 for (int i=0;i<capacity;i++)
   if (data[i].VideoID == '\0')
      return i;
 int firstempty = capacity;
 increaseCapacity();
 return firstempty;    
}

void videoShopSystem::increaseCapacity() //increase storage/list capacity
{
 ListNode* newdata = new ListNode[ capacity*2 ];
 for (int i=0; i<capacity; i++)
    newdata[i] = data[i];
 for (int i=capacity; i<capacity*2; i++)
   {
    newdata[i].VideoID = '\0';
    newdata[i].next = -1;
   } 
 delete[] data;
 data = newdata;
 capacity *= 2;
}

void videoShopSystem::addNewRecord() //implementation of linked list
{
 
     if(size!=capacity)
     {
      if(head == tail) {head = 0; tail = 0;}
      
      cur = tail;
      tail++;
                       
      cout << "Video Record ID: ";
      cin >> data[cur].VideoID;
      cout << "Movie/Video Title: ";
      cin.ignore(1, '\n');
      getline(cin, data[cur].VideoName);
      cout <<endl;
      
      size++;
     }
     else
         cout<< "Capacity reached maximum!!!";
}           

void videoShopSystem::displayRecord()
{
     cout << "Video ID\t\tVideoName" <<endl;
     cout << "----------------------------------"<<endl;
     
     for(int i=head; i<size; i++)
     cout << data[i].VideoID <<"\t\t\t" <<data[i].VideoName<<endl;
      
}
/*
void videoShopSystem::editRecord()
{
     cout << "Enter Record ID: ";
     cin >> data[cur].VideoID;
     



}
*/

void videoShopSystem::saveRecord(string filename) // Save Function
{
   ofstream fout(filename.c_str());
   if (fout.is_open()) 
    {
     if ( empty() ) 
      {
      cout << "Nothing on List. No Save" << endl;
      system("PAUSE");
      
      }else {
      cur = head;//current is at start
      /*while (cur != -1)// not at end
      {
        fout << data[cur].VideoID;
        fout << data[cur].VideoName; 
        cur = data[cur].next;//loop to next until =-1(end)
      }*/
      for(int i=head; i<size; i++) //replace while
     fout << data[i].VideoID <<"\t\t\t" <<data[i].VideoName<<endl;
    }
  } 
  else 
  {
    cerr << "Can't open file " << filename << endl;//incase of error
    system("PAUSE");
    } 
 fout.close();  

}

void videoShopSystem::loadRecord(string filename) // Load Function 
{
  ifstream fin(filename.c_str());
  char item;//declare
  if (fin.is_open()) 
    {
     clear();  //clear the list before reading data
     do 
    {
       item = fin.get();
       if( !fin.eof() )//returns true if end of file has been reached
       push_back(item);// read item
    } 
    while( !fin.eof() );//end of file has not been reached
  } 
  else 
  {
    cerr << "Can't open file " << filename << endl;
    system("PAUSE");
    } 
 fin.close();   
}


void videoShopSystem::displayMainMenu()
{
    cout<< "---------------Video Shop System--------------" <<endl;
    //cout<< "-----------------" <<endl;
    cout<< "           1) Add New Record"<<endl;
    cout<< "           2) View All Records"<<endl;
    cout<< "           3) Edit Record"<<endl;
    cout<< "           4) Delete Record"<<endl;
    cout<< "           5) Save Record"<<endl;
    cout<< "           6) Load Record"<<endl;
    cout<< "           7) Quit"<<endl<<endl;
    
    
    cout<< "Enter Choice: ";

}

void videoShopSystem::menuChoice(int key)
{
    switch(key)
    {
               case 1: cout<<"# Add New Record #"<<endl;
                       addNewRecord();
               break;
               case 2: cout<<"# View All Records #"<<endl;
                       displayRecord();
               break;
               case 3: cout<<"# Edit Record #"<<endl;
                       
               break;
               case 4: cout<<"# Delete Record #"<<endl;
               break;
               case 5: cout<<"# Save Record #"<<endl;   
                       saveRecord("c:\\a_file.txt");                       
               break;
               case 6: cout<<"# Load Record #"<<endl;
                       loadRecord("c:\\a_file.txt");
               break;
               case 7: cout<<"Game Over!"<<endl;
               break;
    }
    system("pause");
    system("cls");  
     
}


int main(){
    
    videoShopSystem obj1;
    string filename;
    int key;
    
    do{
    
    obj1.displayMainMenu();
    cin >>key;
    system("cls");
    obj1.menuChoice(key);
    
    }while(key!=7);
    
    
    //system("pause");
    return 0;
}

I've managed to run the program without any errors but It doesn't give me what I want. After I load an already saved file and try using the display function, the output is a list of numbers instead of what I have saved.

What am I doing wrong ? The load function starts at Line 188

kazek 0 Newbie Poster · Answer 7 · 2008-09-14T08:34:38+00:00

kazek 0 Newbie Poster

16 Years Ago

Anyone ?

miepmuts 10 Newbie Poster · Answer 8 · 2008-09-16T20:16:42+00:00

int get();
Extracts a character from the stream and returns its value (casted to an integer).

So the get function just get's a character and formats it to a string.

You probably want to use the getlinel function, and decompose the line in the ID and the number.