程序如下，输入输出分别为
Sample Input:
Welcome to our party!
The party begins at 9:00.
party
7:00
Sample Output：
–Searching in Email–
We found “party” in
“–Email–
Sender:Teng
Recipient:Wang
Content:Welcome to our party!
”
–Searching in File–
Not Found!
//程序：
#include <iostream>
#include <string>
using namespace std;
class Document
{
protected:
string text;
public:
Document(string te):text(te){};
string getText() const {return text;}
};
class Email:public Document
{
private:
string sender,recipient,Etext;
public:
Email(string se,string re):Document(string()),sender(se),recipient(re){};  //!!!!!!!!!!
void setText(string text1){Etext=text1;}
friend ostream & operator<<(ostream &output,Email &email)
{
cout<<“–Email–“<<endl<<“Sender:”;
output<<email.sender<<endl<<“Recipient:”<<email.recipient<<endl<<“Content:”<<email.Etext<<endl;
return output;
}
};
class File:public Document
{
private:
string path,Ftext;
public:
File(string pa,string Ft):Document(Ft),path(pa){};
void setText(string text1){Ftext=text1;}
friend ostream & operator<<(ostream &output,File &file)
{
cout<<“–File–“<<endl<<“Path:”;
output<<file.path<<endl<<“Content:”<<file.Ftext<<endl;
return output;
}
};
bool ContainsKeyword(const Document& docObject,string keyword)
{
if (docObject.getText().find(keyword) != string::npos)
return true;
return false;
}
int main()
{
string word,text;
Email testEmail(“Teng”,”Wang”);
File testFile(“c:\documents\myfile”,”The party begins at 7:00pm.”);
getline(cin,text);
testEmail.setText(text);
getline(cin,text);
testFile.setText(text);
cout<<“–Searching in Email–“<<endl;
cin>>word;
if(ContainsKeyword(testEmail,word))
cout<<“We found “”<<word <<“” in \n””<<testEmail<<“””<<endl;
else
cout<<“Not Found!”<<endl;
cout<<“–Searching in File–“<<endl;
cin>>word;
if(ContainsKeyword(testFile,word))
cout<<“We found “”<<word <<“” in \n””<<testFile<<“””<<endl;
else
cout<<“Not Found!”<<endl;
return 0;
}