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这是C++的一部分练习程序!对初学者有一定的帮助作用。

#include <iostream.h>
#include <string.h>
class String
{
  public:
	String()
	{  Length=0;Buffer=0;  }
	String(const char *str)
	{
		Length=strlen(str);
		Buffer=new char[Length+1];
		strcpy(Buffer,str);
	}
	void Setc(int index,char newchar)
	{
		if(index>0&&index<=Length)
			Buffer[index]=newchar;
	}
	char Getc(int index) 
	{
		if(index>0&&index<=Length)
			return Buffer[index-1];
		else
			return 0;
	}
	int GetLength()
	{  return Length;  }
	void Print()
	{
		if(Buffer==0)
			cout<<"Empty.\n";
		else
			cout<<Buffer<<endl;
	}
	void Append(const char *);
	~String()
	{  delete []Buffer;  }
  private:
	int Length;
	char *Buffer;
};
void String::Append(const char *Tail)
{
	char *tmp;
	Length+=strlen(Tail);
	tmp=new char[Length+1];
	strcpy(tmp,Buffer);
	strcat(tmp,Tail);
	delete []Buffer;
	Buffer=tmp;
}

void main()
{
	String s0,s1("a string.");
	s0.Print();
	s1.Print();
	cout<<s1.GetLength()<<endl;
	s1.Setc(5,'p');
	s1.Print();
	cout<<s1.Getc(6)<<endl;
	String s2("this ");
	s2.Append("a string.");
	s2.Print();
}