fig4_3.cpp

重载＋＝为字符串的连接

//fig4_3.cpp
//测试类String的程序
#include <iostream.h>
#include "string2.h"

main()
{
	String s1("happy"), s2("birthday"), s3(" ");
	//测试重载的相等运算符和关系运算符
	cout<<"s1 is \""<<s1<<"\"; s2 is \""<<s2<<"\"; s3 is empty \n"
		<<"The results of comparing s2 and s1:"
		<<"\ns2==s1 yields"<<(s2==s1)
		<<"\ns2!=s1 yields"<<(s2!=s1)
		<<"\n s2>s1 yields"<<(s2>s1)
		<<"\ns 2<s1 yields"<<(s2<s1)
		<<"\ns2>=s1 yields"<<(s2>=s1)
		<<"\ns2<=s1 yields"<<(s2<=s1)<<"\n\n";

	//测试重载运算符!(改运算符用来测试对象是否为空)
	cout<<"Testing!s3: \n";
	if(!s3){
		cout<<"s3 is empty; assigning s1 to s3; \n";
		s3=s1;	//测试重载的赋值运算符
		cout<<"s3 is \""<<s3<<"\"\n\n";
	}

	//测试重载的连接运算符
	cout<<"s1+=s2 yields";
	s1+=s2;	//测试重载的连接运算符
	cout<<"s1="<<s1<<"\n\n";

	//测试转换构造函数
	cout<<"s1+=\"to you\"yields\n";
	s1+="to you";	//测试转换构造函数
	cout<<"s1="<<s1<<"\n\n";

	//测试用于子串的重载的函数调用运算符()
	cout<<"The substring of s1 starting at \n"
		<<"location 0 for 14 characters, s1(0, 14), is:"
		<<s1(0, 14)<<"\n\n";

	//测试到子串尾的子串
	cout<<"The substring of s1 starting at \n"
		<<"location 15, s1(15, 0) is:"
		<<s1(15, 0)<<"\n\n";	//0意味着串尾
	
	//测试拷贝构造函数
	String *s4Ptr=new String(s1);
	cout<<"*s4Ptr="<<*s4Ptr<<"\n\n";

	//测试自我赋值时的赋值运算符=
	cout<<"assigning *s4Ptr to *s4Ptr\n";
	*s4Ptr=*s4Ptr;	//测试自我赋值
	cout<<"*s4Ptr="<<*s4Ptr<<endl;

	//测试析构函数
	delete s4Ptr;

	//测试用下标运算符建立左值
	s1[0]='H';
	s1[6]='B';
	cout<<"\ns1 after s1[0]='H' and s1[6]='B' is:"
		<<s1<<"\n\n";

	//测试下标是否越界
	cout<<"Attempt to assign 'd' to s1[30] yields: \n";
	s1[30]='d';	//错误：下标越界

	return 0;
}