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Getting Junk Values for Sequence Container Class

davydany
P: 4
Hey guys...a n00b Here for this site.
I'm making a sequence class for my C++ class. And The thing is in the array that I have, lets say i put in {13,17,38,18}, when i see the current values for the array data[current_index] from 0 to3, I get this {13, JUNK VALUE, 17,38, 18} and JUNK VALUE is like 1.8e831 or something like that.

This happens when I use the attach() function and use the current() function to display the values at data[current_index]

I really want to thank you for your help. Anything else you need, please post, I'll put it up. Thank You!

BTW, This is in Windows XP Home using Visual C++

Here is my header file:

[PHP]
// FILE: sequence1.h
// CLASS PROVIDED: sequence (part of the namespace main_savitch_3)
// There is no implementation file provided for this class since it is
// an exercise from Section 3.2 of "Data Structures and Other Objects Using C++"
//
// TYPEDEFS and MEMBER CONSTANTS for the sequence class:
// typedef ____ value_type
// sequence::value_type is the data type of the items in the sequence. It
// may be any of the C++ built-in types (int, char, etc.), or a class with a
// default constructor, an assignment operator, and a copy constructor.
//
// typedef ____ size_type
// sequence::size_type is the data type of any variable that keeps track of
// how many items are in a sequence.
//
// static const size_type CAPACITY = _____
// sequence::CAPACITY is the maximum number of items that a sequence can hold.
//
// CONSTRUCTOR for the sequence class:
// sequence( )
// Postcondition: The sequence has been initialized as an empty sequence.
//
// MODIFICATION MEMBER FUNCTIONS for the sequence class:
// void start( )
// Postcondition: The first item on the sequence becomes the current item
// (but if the sequence is empty, then there is no current item).
//
// void advance( )
// Precondition: is_item returns true.
// Postcondition: If the current item was already the last item in the
// sequence, then there is no longer any current item. Otherwise, the new
// current item is the item immediately after the original current item.
//
// void insert(const value_type& entry)
// Precondition: size( ) < CAPACITY.
// Postcondition: A new copy of entry has been inserted in the sequence
// before the current item. If there was no current item, then the new entry
// has been inserted at the front of the sequence. In either case, the newly
// inserted item is now the current item of the sequence.
//
// void attach(const value_type& entry)
// Precondition: size( ) < CAPACITY.
// Postcondition: A new copy of entry has been inserted in the sequence after
// the current item. If there was no current item, then the new entry has
// been attached to the end of the sequence. In either case, the newly
// inserted item is now the current item of the sequence.
//
// void remove_current( )
// Precondition: is_item returns true.
// Postcondition: The current item has been removed from the sequence, and the
// item after this (if there is one) is now the new current item.
//
// CONSTANT MEMBER FUNCTIONS for the sequence class:
// size_type size( ) const
// Postcondition: The return value is the number of items in the sequence.
//
// bool is_item( ) const
// Postcondition: A true return value indicates that there is a valid
// "current" item that may be retrieved by activating the current
// member function (listed below). A false return value indicates that
// there is no valid current item.
//
// value_type current( ) const
// Precondition: is_item( ) returns true.
// Postcondition: The item returned is the current item in the sequence.
//
// VALUE SEMANTICS for the sequence class:
// Assignments and the copy constructor may be used with sequence objects.

#ifndef MAIN_SAVITCH_SEQUENCE_H
#define MAIN_SAVITCH_SEQUENCE_H
#include <cstdlib> // Provides size_t

namespace main_savitch_3
{
class sequence
{
public:
// TYPEDEFS and MEMBER CONSTANTS
typedef double value_type;
typedef size_t size_type;
static const size_type CAPACITY = 30;
// CONSTRUCTOR
sequence( );
// MODIFICATION MEMBER FUNCTIONS
void start( );
void advance( );
void insert(const value_type& entry);
void attach(const value_type& entry);
void remove_current( );
// CONSTANT MEMBER FUNCTIONS
size_type size( ) const;
bool is_item( ) const;
value_type current( ) const;
private:
value_type data[CAPACITY];
size_type used;
size_type current_index;
};
}

#endif
[/PHP]

This is my implimentation file
[PHP]
//File: sequenceImpliment.cpp
//CLASS Implimented: sequence (see sequence1.h for more documentation)

#include <cassert>
#include <cmath>
#include <iostream>
#include "sequence1.h"

namespace main_savitch_3
{
//CONSTRUCTORS
sequence::sequence()
// Postcondition: The sequence has been initialized as an empty sequence.
{
used = 0;
current_index = 0;
}

//VOID MEMBER Functions
void sequence::start( )
// Postcondition: The first item on the sequence becomes the current item
// (but if the sequence is empty, then there is no current item).
{
current_index = 0;
}
void sequence::advance( )
// Precondition: is_item returns true.
// Postcondition: If the current item was already the last item in the
// sequence, then there is no longer any current item. Otherwise, the new
// current item is the item immediately after the original current item.
{
if(current_index<used)
current_index++;
else
current_index=0;

}
void sequence::insert(const value_type& entry)
// Precondition: size( ) < CAPACITY.
// Postcondition: A new copy of entry has been inserted in the sequence
// before the current item. If there was no current item, then the new entry
// has been inserted at the front of the sequence. In either case, the newly
// inserted item is now the current item of the sequence.
{
if(size()<CAPACITY)
{
if(current_index==0)
{
data[0]=entry;
used++;
current_index++;

}
else if(current_index<=used)
{
used++;
for (int i=used; i>=current_index;i--)
{
data[i]=data[i-1];
}
data[current_index]=entry;
}
}
}
void sequence::attach(const value_type& entry)
// Precondition: size( ) < CAPACITY.
// Postcondition: A new copy of entry has been inserted in the sequence after
// the current item. If there was no current item, then the new entry has
// been attached to the end of the sequence. In either case, the newly
// inserted item is now the current item of the sequence.
{
if(size()<CAPACITY)
{
if(current_index==0)
{
data[0]=entry;
used++;
current_index++;

}
else if(current_index<=used)
{
used++;
for (int i=used; i>=current_index+1;i--)
{
data[i]=data[i-1];
}
current_index++;
data[current_index]=entry;

}
}
}
void sequence::remove_current( )
// Precondition: is_item returns true.
// Postcondition: The current item has been removed from the sequence, and the
// item after this (if there is one) is now the new current item.
{
if(is_item())
{
if(current_index!=used)
{
for(int i=current_index;i<=used;i++)
data[i]=data[i+1];
data[used]=0;
used--;
}
else
{
data[current_index]=0;
current_index--;
used--;
}
}
}

//CONSTANT MEMBERS FUNCTIONS
sequence::size_type sequence::size() const
// Postcondition: The return value is the number of items in the sequence.
{
return used;
}

bool sequence::is_item( ) const
// Postcondition: A true return value indicates that there is a valid
// "current" item that may be retrieved by activating the current
// member function (listed below). A false return value indicates that
// there is no valid current item.
{

if(current_index<=used)
return 1;
else
return 0;
}
sequence::value_type sequence::current( ) const
// Precondition: is_item( ) returns true.
// Postcondition: The item returned is the current item in the sequence.
{
if(is_item())
//return data[current_index];
return current_index;
}
}
[/PHP]
Feb 26 '07 #1
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1 Reply


P: 1
Did you ever get a response to this? I'm working on the same exact problem for a C++ class and getting similar stuff, junk data getting inserted into the array. Would love to know if you got this working yet...
Mar 17 '07 #2

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