8-1(

C++多态性程序例子

#include <iostream.h>
#include <string.h>

class string
{
public:
	string(char *s);
	string(string &s1);
	string(int size=80);
	~string() { delete sptr; }
	int getlen() { return length; }
	void print() { cout<<sptr<<endl; }
private:
	char *sptr;
	int length;
};

string::string(char *s)
{
	length = strlen(s);
	sptr = new char[length+1];
	strcpy(sptr, s);
}

string::string(string &s1)
{
	length = s1.length;
	sptr = new char[length+1];
	strcpy(sptr, s1.sptr);
}

string::string(int size)
{
	length = size;
	sptr = new char[length+1];
	*sptr = '\0';
}

void main()
{
	string str1("This is a string.");
	str1.print();
	cout<<str1.getlen()<<endl;
	char *s1 = "That is a program.";
	string str2(s1);
	string str3(str2);
	str3.print();
	cout<<str3.getlen()<<endl;
}