Core dump segment fault

[Dee76]

Everything compiles no warnings or errors, but after I run this I get a core dump if I uncomment "delete [] a;" at the end of the main() function. It seems to run correctly if I leave "delete [] a;" commented out? Any suggestions will be appreciated.

#include <iostream>
using namespace std;

typedef unsigned int size_t;
size_t size = 0; // Initialize the size of the array
int* a = new int[size]; // Create a dynamic array

float Median(int* a, size_t size); // Median function declaration
float Mean(int* a, size_t size); // Mean function declaration
void Swap(int& x, int& y); // Swap function declaration
void Sort(int* a, size_t size); // Sort function declaration


int main()
{

  cout << "Enter integers (any character to quit): ";
  
  int n = 0;
   
  // Loop through user's integers
  while((std::cin >> n) && (size < 100))
  {

    a[size] = n; 
    size++;
 
  }

  // Output the Input Values
  cout << '\n';
  cout << "Input values:    ";
       
  if(size != 0)
    {
      for(size_t d=0;d<size;d++)
	{
	       
	  cout << a[d] << " ";
 
	}
    }

  // Output the Mean
  cout << '\n';
  cout << "Mean:    " << Mean(a, size) << '\n'; 

  // Output the Median
  cout << "Median:  " << Median(a, size) << '\n';

  // Output the Sorted Input Values
  cout << "Sorted input values:  ";
  if(size != 0)
    {
      for(size_t e=0;e<size;e++)
	{

	  cout << a[e] << " ";

	}
    }

  cout << '\n';

  // delete the array (I get a core dump error when uncommented)
  //delete [] a;

  return 0;

} // End of main


// Calculate the Mean of the array, function body of Mean
float Mean(int* a, size_t size)
{

  float mean;
  if(size != 0)
    {

      float sum = 0;
      for(size_t i=0;i<size;++i)
	{

	  sum += a[i];
       
	}

      mean = sum/size;

    }
  else
    {

      mean = 0;

    }

  return mean;

} // End of function Mean


// Calculate the Median of the array, function body of Median
float Median(int* a, size_t size)
{

  // Sort the array from smallest to largest
  if(size != 0)
    {
      Sort(a, size);
    }

  float median;


  if((size%2 == 0) && (size != 0))
    {

      // median if size is even
      median = ((a[size/2] + a[size/2-1])/2.0F);
      
    }
  else if(size != 0)
    {

      // median if size is odd
      median = a[(size-1)/2];
      
    }
  else
    {

      median = 0;

    }

  return median;

}


// Sort the array
void Sort(int* a, size_t size)
{

  for(size_t i = 0;i<size-1;i++)
    {
      int k = i;
      for(size_t j=i+1;j<size;j++)
	{

	  if(a[j] < a[k])
	    {
	      k = j;
	    }

	}
      
    // Call function Swap
    Swap(a[i], a[k]);

    }

} // End function Sort

// Swap Values in array
void Swap(int& x, int& y)
{

  int temp = x;
  x = y;
  y = temp;

}

[vijayan121]

// ...
size_t size = 0; // Initialize the size of the array
int* a = new int[size]; // Create a dynamic array *** of size 0? ***
// ...

[Dee76]

Thanks. I guess in C++ you can't resize a dynamic array like I was trying to.

[Salem]

You need to specify the max size up front. const int maxSize = 100; Then int* a = new int[maxSize]; // Create a dynamic array Then while((std::cin >> n) && (size < maxSize)) Though to be honest, you should really start with a std::vector<int> a(maxSize); which takes care of all that memory management stuff for you.

[Dee76]

Thanks for the information. We haven't used vectors yet. From what I've read in these forums that's the best way to go.