sysdyn.h

A Dynamic Array is a resizable collection implemented as an array. The System::DynamicArray template is a C++ implementation of Delphi Dynamic Array types. The System::DynamicArray template uses a binary layout compatible with the Delphi Dynamic Array implementation.

template <class T> class DELPHIRETURN DynamicArray;

You must specify one template parameter:

Length of dynamic arrays 

The size of a System::DynamicArray can be set or obtained from the Length property: 

//C++ example

DynamicArray<int> arrayOfInt;
arrayOfInt.Length = 10;
cout << "ArrayLength: " << arrayOfInt.Length << endl;

To free a System::DynamicArray, assign it a Length of zero. 

Accessing data 

Access elements of a Dynamic Array via the subscript [] operator:  

//C++ example

void InitArray(DynamicArray<char> &c_array)
{
  c_array[0] = 'A';
  c_array[1] = 'B';
  cout << "Third char is: " << c_array[2];
}

Bounds of dynamic arrays 

The Low and High properties of System::DynamicArrays return the low and high bounds of the array respectively. 

//C++ example

int TotalArray(const DynamicArray<int>& arrayOfInt)
{
int total=0;
for (int i=arrayOfInt.Low; i<=arrayOfInt.High; i++)
    total += arrayOfInt[i];
return total;
}

Assigning, comparing and copying dynamic arrays 

Dynamic Arrays are reference counted. When a System::DynamicArray is assigned to another, only the reference is assigned (and the reference count adjusted), the content of the source is not copied. Similarly, when two Dynamic Arrays are compared, only the references are compared, not the contents. To copy the contents of a System::DynamicArray, you must use the Copy (or CopyRange) methods. 

//C++ example

void foo(DynamicArray<int> &i_array)
{
  DynamicArray<int> temp = i_array;
  assert(temp == i_array); // temp and i_array point to same chunk 
                           // of data..
  i_array[0] = 20;
  assert(temp[0] == 20); // Temp 'sees' changes to i_array..
  temp = i_array.Copy(); // Temp gets its own copy of data
  temp[0] = 10;
  assert(temp[0] != i_array[0]); // Above assignment did not 
                                 // modify i_array.
}

Multidimensional dynamic arrays 

Dynamic arrays can be multidimensional. Multidimensional dynamic arrays don't have to be rectangular. The Length property can be used to set each dimension. The following example illustrates. 

//C++ example

typedef DynamicArray< DynamicArray < AnsiString > > T2DStringArray;
void foo(T2DStringArray &s_array)
{
  SetLength(s_array, 10);
for (int i=0; i<s_array.Length; i++)
  { // Set lengths of second dimensions.(NOTE: non-rectangular) 
    SetLength(s_array[i], i+1); 
for (int j=0; j<s_array[i].Length; j++)
    /* */ s_array[i][j] = itoa(i*10+j);
  }
}

C++ & Delphi System::DynamicArrays 

A dynamic array declared in C++ code can be used in Delphi code and vice versa. The following examples illustrate passing a one-dimensional and two-dimensional array between C++ and Delphi. 

C++ System::DynamicArray Example 

Delphi System::DynamicArray Example