array.cc

做为SD0609的一员,我扎实的基础是如何打出来的,来看看我那时连猴子选大王都不会的人,是如何成长起来的吧!主要包括我所做的C++,JAVA基础联系.乱是乱了点,不过如果真心想学习,打好基础,看看也不

#include <iostream>
using namespace std;

class Array{
	int* p;//the start address of variable group
	int num;//the number of elements
public:
	Array( int len );//allocate space
	~Array();//release space
	int& at( int );//access elements by index
	void output();//show all the elements
	void resize( int len );//change length
	int size(){ return num; }
};

Array::Array( int len )
{
	if( len<1 )
	{
		cout << "invalid length!" << endl;
		len = 1;
	}
	num = len;
	p = new int[num];
	cout << "address:" << p << endl;
}
Array::~Array()
{
	cout << "release:" << p << endl;
	delete[] p;
}
int& Array::at( int index )
{
	if( index<0 || index>=num )
	{
		cout << "invalid index!" << endl;
		index = 0;
	}
	return p[index];
}
void Array::output()
{
	for( int i=0; i<num; i++ )
	{
		cout << p[i] << ' ';
	}
	cout << endl;
}
void Array::resize( int len )
{
	if( len<1 )
		return;
	int* pn = new int[len];
	int min = num<len?num:len;
	for( int i=0; i<min; i++ )
	{
		pn[i] = p[i];
	}
	cout << "old address:" << p << endl;
	delete[] p;
	p = pn;
	num = len;
	cout << "new address:" << p << endl;
}
int main(int argc, char* argv[])
{
	Array a(10);
	a.output();
	for( int i=0; i<a.size(); i++ )
	{
		a.at(i) = 10+i;
	}
	a.output();
	a.resize(5);
	a.output();
	a.resize(10);
	a.output();
	return 0;
}