I'm supposed to dynamically allocate an array of integers. The function should accept an integet argument indicating teh number of elements to allocate. The function should return a pointer to the array.

This is what i got so far.

#include <iostream>
using namespace std;

//Function prototype
int *arrAllocator(int);
int numElements;
int num;
int count; //Loop counter

int main()
{
	int *values; //To point to the numbers

	//Get an array of number chosen by user. 
	values = arrAllocator(numElements);

	cout << "\nEnter an array size: " << endl;
	cin >> numElements;

	//Get number values from user.
	cout << "Enter the value of the elements below.\n";

	for (count = 0; count < numElements; count++)
	{
	cout << "Value #" << (count + 1) << ": ";
	cin >> values[count];
	}

	//Display the numbers.
	for (int count = 0; count < numElements; count++)
		cout << values[count] << endl;

	//Free the memory.
	delete [] values;
	values = 0;
	return 0;
}

//The function returns a pointer to an array.

int *arrAllocator(int numElements)
{
	int *array;

	//Invalid if zero or negative.
	if (numElements <= 0)
		return NULL;

	//Dynamically allocate the array.
	array = new int[num];
	
	//Return a pointer to the array
	return array;
}

The program will start to run normal but after the user inputs the first number in the array it stops for errors. I know that a my mistakes are more than likely in returning the pointer to the array. But i can't figure it out i even wonder if maybe i linked some of the names incorrectly. Could some one please assist in telling me where im messing up, or did i go about writting the program incorrectly. Thank you in advance.

in the future, please use [ code] [/ code] tags, as it makes your code so much more readable. Formatted here

#include <iostream>
using namespace std;

//Function prototype
int *arrAllocator(int);
int numElements;
int num;
int count; //Loop counter

int main()
{
int *values; //To point to the numbers

//Get an array of number chosen by user.
values = arrAllocator(numElements);

cout << "\nEnter an array size: " << endl;
cin >> numElements;

//Get number values from user.
cout << "Enter the value of the elements below.\n";

for (count = 0; count < numElements; count++)
{
cout << "Value #" << (count + 1) << ": ";
cin >> values[count];
}

//Display the numbers.
for (int count = 0; count < numElements; count++)
cout << values[count] << endl;

//Free the memory.
delete [] values;
values = 0;
return 0;
}

//The function returns a pointer to an array.

int *arrAllocator(int numElements)
{
int *array;

//Invalid if zero or negative.
if (numElements <= 0)
return NULL;

//Dynamically allocate the array.
array = new int[num];

//Return a pointer to the array
return array;
}

Now, as to your actual question:

The first error I see is that you use numElements before it gets set.
move values = arrAllocator(numElements); to after cin >> numElements; , and that problem will be solved.

After just a quick reading of the code, that is the only problem I can find.

I fixed the and moved the values = arrayAllocator(numElements); to after the cin >> numElements;

That did help in making the program ask for the rest of the values, but at the very end after it displays the array i still get an error. that says crt detected that the application wrote to memory after end of heap buffer.

It's better to wrap code tags in noparse tags to avoid putting spaces here and there just to make it look like a code tag :P

Edited 3 Years Ago by happygeek: fixed formatting

pltndragon,
Some suggestions for you:
numElements is declared at file context (global) and hence it's value is 0.

values = arrAllocator(numElements);   //  arrAllocatator(0) ?

First, read value into numElements and then go for allocation.

cout << "\nEnter an array size: " << endl;
 cin >> numElements;
 values = arrAllocator(numElements);

PS: Avoid global declaration of variables if possible. numElements is global variable and you are passing as an argument. It's an improper way.

In arrAllocator() Function, num is global variable with 0 value.

//Dynamically allocate the array.
   array = new int[num]; // <--- new int[numElements]

There are some problems with count variable(s) in main().

::count   //   external count
  for(int count= ..) // local - block var.

Finally, your code should be:

#include <iostream>
using namespace std;

//Function prototype
int *arrAllocator(int);

int main()
{
   int *values; //To point to the numbers
   int numElements;
   int count; //Loop counter

   cout << "\nEnter an array size: " << endl;
   cin >> numElements;
   values = arrAllocator(numElements);
   if(values==NULL) 
      return 0;

   //Get number values from user.
   cout << "Enter the value of the elements below.\n";
    for (count = 0; count < numElements; count++)
    {
      cout << "Value #" << (count + 1) << ": ";
       cin >> values[count];
      }

   //Display the numbers.
   for (count = 0; count < numElements; count++)
     cout << values[count] << endl;

   //Free the memory.
   delete [] values;
return 0;
}

//The function returns a pointer to an array.
int *arrAllocator(int numElements)
{
int *array;
   //Invalid if zero or negative.
   if (numElements <= 0)
       return NULL;
   //Dynamically allocate the array.
   array = new int[numElements];

   //Return a pointer to the array
  return array;
}

Thank you, for your help and letting me know what i was doing wrong and why it was wrong. I have defently learned a bit more from your explanations.

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