RSS

"Safe array" assignment

Please support our C++ advertiser: Programming Forums

Views: 3246 | Replies: 1 | Thread Tools Display Modes

•

Join Date: Jul 2004

Location: North East Indiana

Posts: 491

Reputation: Puckdropper is an unknown quantity at this point

Rep Power: 5

Solved Threads: 20

Puckdropper Puckdropper is offline

Offline

Posting Pro in Training

"Safe array" assignment

Sep 12th, 2005

Hello,

I've been trying to write a program for a class I'm taking, and have gotten stuck on part of the assignment.

The program is to:

•

9> Create a template for a safe array. The user will be able to designate the element type and the size of the array. The operations will ensure that no access is allowed outside the bounds of the array. Operations will include [], =, and ==. Instantiate several arrays of different types and sizes and show that the safety features work.

I have the class and template set up, as shown here:

Help with Code Tags

(Toggle Plain Text)

template <class datatype, int size>
class safe_array
  {
	private:
	//Note: array format: TYPE Name[element]
  datatype thearray[size]; 
	bool checkbounds(int ub);  //Return true if good, false if not.
	
	public:
	safe_array();
  ~safe_array();
	datatype operator [] (int index);
 	datatype operator = (datatype value);
	datatype operator == (safe_array& array1);

  //These are temporary.  They will be used in testing.
  void fill();
	void print();
	};

The rest of the definition is as follows:

Help with Code Tags

(Toggle Plain Text)

template <class datatype, int size>
safe_array<datatype, size>::safe_array()
  {
	}

template <class datatype, int size>
safe_array<datatype, size>::~safe_array()
  {
	}

template <class datatype, int size>
bool safe_array<datatype, size>::checkbounds(int ub)
//bool checkbounds(int ub)
  {
  //ub--upper bound
	if (ub <= size)
	  {
		return true;
		}
	else
		{
	  return false;
		}
	}

template <class datatype, int size>
datatype safe_array<datatype, size>::operator [](int index)
  {
  bool goodornot;
	goodornot =	checkbounds(index);
	if (goodornot)
	  return thearray[index];
	else
	  {
		cout << "Run-time error:  Index out of bounds.";
		cerr << "Index out of bounds!!!";
		return -1;
		}
	}
	
template <class datatype, int size>
datatype safe_array<datatype, size>::operator = (datatype value)
  {
  
	}

template <class datatype, int size>	
datatype safe_array<datatype, size>::operator == (safe_array& array1)
  {
	}
	
//Temporary
template <class datatype, int size>
void safe_array<datatype, size>::fill()
	{
	cin >> thearray[1];
	cin >> thearray[2];
	cin >> thearray[3];
	cin >> thearray[4];
	}

template <class datatype, int size>
void safe_array<datatype, size>::print()
	{
	cout << thearray[1] << endl;
	cout << thearray[2] << endl;
	cout << thearray[3] << endl;
	cout << thearray[4] << endl;
	}

The template is instantiated with:

Help with Code Tags

(Toggle Plain Text)

	safe_array<char, 5> dosomething;

What I want is for this line:

Help with Code Tags

(Toggle Plain Text)

dosomething[5] = 'w';

to do what it would normally do using an array. I'm stuck on writing the assignment operator and lengthy web searches have returned no useful results. What do I need to do?

www.uncreativelabs.net

Old computers are getting to be a lost art. Here at Uncreative Labs, we still enjoy using the old computers. Sometimes we want to see how far a particular system can go, other times we use a stock system to remind ourselves of what we once had.