二阶构造函数

class IntArray
{
private:
int m_length;
int* m_pointer;

IntArray(int len);
IntArray(const IntArray& obj);
bool construct();
public:
static IntArray* NewInstance(int length);
int length();
bool get(int index, int& value);
bool set(int index ,int value);
~IntArray();
};
IntArray::IntArray(int len)
{
m_length = len;
}

bool IntArray::construct()
{
bool ret = true;

m_pointer = new int[m_length];

if( m_pointer )
{
for(int i=0; i<m_length; i++)
{
m_pointer[i] = 0;
}
}
else
{
ret = false;
}

return ret;
}

IntArray* IntArray::NewInstance(int length)
{
IntArray* ret = new IntArray(length);

if( !(ret && ret->construct()) )
{
delete ret;
ret = 0;
}

return ret;
}

int IntArray::length()
{
return m_length;
}

bool IntArray::get(int index, int& value)
{
bool ret = (0 <= index) && (index < length());

if( ret )
{
value = m_pointer[index];
}

return ret;
}

bool IntArray::set(int index, int value)
{
bool ret = (0 <= index) && (index < length());

if( ret )
{
m_pointer[index] = value;
}

return ret;
}

IntArray::~IntArray()
{
delete[]m_pointer;
}