001:MyString

描述

补足MyString类，使程序输出指定结果

#include <iostream>
#include <string>
#include <cstring>
using namespace std;
class MyString {
	char * p;
public:
	MyString(const char * s) {
		if( s) {
			p = new char[strlen(s) + 1];
			strcpy(p,s);
		}
		else
			p = NULL;

	}
	~MyString() { if(p) delete [] p; }
// 在此处补充你的代码
};
int main()
{
	char w1[200],w2[100];
	while( cin >> w1 >> w2) {
		MyString s1(w1),s2 = s1;
		MyString s3(NULL);
		s3.Copy(w1);
		cout << s1 << "," << s2 << "," << s3 << endl;

		s2 = w2;
		s3 = s2;
		s1 = s3;
		cout << s1 << "," << s2 << "," << s3 << endl;
		
	}
}

输入

多组数据，每组一行，是两个不带空格的字符串

输出

对每组数据，先输出一行，打印输入中的第一个字符串三次
然后再输出一行，打印输入中的第二个字符串三次

样例输入

abc def
123 456

样例输出

abc,abc,abc
def,def,def
123,123,123
456,456,456

 我写的时候一直RE，然后我从oj上把那组数据下载下来了，我的程序的输出明明和oj上的数据是一模一样的。但是交上去就是RE，后来找了很久的原因，原来是我没有重载MyString & operator=(const MyString &ms) 这个函数。

 

#include <iostream>
#include <string>
#include <cstring>
using namespace std;
class MyString {
	char * p;
public:
	MyString(const char * s) {
//		printf("initial \n");
		if( s) {
			p = new char[strlen(s) + 1];
			strcpy(p,s);
		}
		else
			p = NULL;
	}
	~MyString() { if(p) delete [] p; }
// 在此处补充你的代码
	MyString(const MyString &str){
//		printf("copy constructor\n");
		if(this==&str) return ;
		if(str.p){
			p=new char[strlen(str.p)+1];
			strcpy(p,str.p);
		}
		else{
			if(p) delete [] p;
			p=NULL;
		}
	}
	MyString & operator=(const char *str){
//		printf("overload = const char *\n");
		
		if(p) delete [] p;
		if(str){
			p=new char[strlen(str)+1];
			strcpy(p,str);
		}else{
			p=NULL;
		}
		return *this;
	}
	MyString & operator=(const MyString &ms){
//		printf("operator = MyString\n");
		if(this==&ms) return *this;
		if(p) delete [] p;
		p=new char[strlen(ms.p)+1];
		strcpy(p,ms.p);
		return *this;
	}
	MyString& Copy(const char *str){
//		printf("copy()\n");
		
		if(p) delete [] p;
		if(str){
			p=new char[strlen(str)+1];
			strcpy(p,str);
		}else{
			p=NULL;
		}
		return *this;
	}
	friend ostream & operator<<(ostream &os,const MyString &str){
//		printf("overload << \n");
		os<<str.p;
		return os;
	}
};

int main()
{
	freopen("C:\\Users\\Ambition\\Desktop\\in.txt","r",stdin);
//	freopen("C:\\Users\\Ambition\\Desktop\\out.txt","w",stdout);
	char w1[200],w2[100];
	while( cin >> w1 >> w2) {
		MyString s1(w1),s2 = s1; 
		MyString s3(NULL);
		s3.Copy(w1);
		cout << s1 << "," << s2 << "," << s3 << endl;

		s2 = w2;
		s3 = s2;
		s1 = s3;
		cout << s1 << "," << s2 << "," << s3 << endl;
	}
}