driverprogram.cpp

24学时攻克C++光盘源代码 深入浅出 方便实用

 // Listing 22.3
 #include <iostream>
 #include <string.h>
 
 typedef unsigned long pDate;
 enum SERVICE { PostMaster, Interchange, 
     CompuServe, Prodigy, AOL, Internet };
 
 class String
 {
 public:
     // constructors
     String();
     String(const char *const);
     String(const String &);
     ~String();
 
     // overloaded operators
     char & operator[](int offset);
     char operator[](int offset) const;
     String operator+(const String&);
     void operator+=(const String&);
     String & operator= (const String &);
     friend std::ostream & operator<<
 		(std::ostream& theStream, String& theString);
     // General accessors
     int GetLen()const { return itsLen; }
     const char * GetString() const { return itsString; }
     // static int ConstructorCount;
 
 private:
     String (int);         // private constructor
     char * itsString;
     int itsLen;
 };
 
 // default constructor creates string of 0 bytes
 String::String()
 {
     itsString = new char[1];
     itsString[0] = '\0';
     itsLen=0;
     // std::cout << "\tDefault string constructor\n";
     // ConstructorCount++;
 }
 
 // private (helper) constructor, used only by
 // class methods for creating a new string of
 // required size.  Null filled.
 String::String(int len)
 {
     itsString = new char[len+1];
     int i;
     for ( i = 0; i<=len; i++)
         itsString[1] = '\0';
     itsLen=len;
     // std::cout << "\tString(int) constructor\n";
     // ConstructorCount++;
 }
 
 // Converts a character array to a String
 String::String(const char * const cString)
 {
     itsLen = strlen(cString);
     itsString = new char[itsLen+1];
     int i;
     for ( i = 0; i<itsLen; i++)
         itsString[i] = cString[i];
     itsString[itsLen]='\0';
     // std::cout << "\tString(char*) constructor\n";
     // ConstructorCount++;
 }
 
 // copy constructor
 String::String (const String & rhs)
 {
     itsLen=rhs.GetLen();
     itsString = new char[itsLen+1];
     int i;
     for (i = 0; i<itsLen;i++)
         itsString[i] = rhs[i];
     itsString[itsLen] = '\0';
     // std::cout << "\tString(String&) constructor\n";
     // ConstructorCount++;
 }
 
 // destructor, frees allocated memory
 String::~String ()
 {
     delete [] itsString;
     itsLen = 0;
     // std::cout << "\tString destructor\n";
 }
 
 String& String::operator=(const String & rhs)
 {
     if (this == &rhs)
         return *this;
     delete [] itsString;
     itsLen=rhs.GetLen();
     itsString = new char[itsLen+1];
     int i;
     for (i = 0; i<itsLen;i++)
         itsString[i] = rhs[i];
     itsString[itsLen] = '\0';
     return *this;
     // std::cout << "\tString operator=\n";
 }
 
 //non constant offset operator, returns
 // reference to character so it can be changed
 char & String::operator[](int offset)
 {
     if (offset > itsLen)
         return itsString[itsLen-1];
     else
         return itsString[offset];
 }
 
 // constant offset operator for use
 // on const objects (see copy constructor!)
 char String::operator[](int offset) const
 {
     if (offset > itsLen)
         return itsString[itsLen-1];
     else
         return itsString[offset];
 }
 
 // creates a new string by adding current
 // string to rhs
 String String::operator+(const String& rhs)
 {
     int  totalLen = itsLen + rhs.GetLen();
     String temp(totalLen);
     int i,j;
     for (i = 0; i<itsLen; i++)
         temp[i] = itsString[i];
     for (j = 0; j<rhs.GetLen(); j++, i++)
         temp[i] = rhs[j];
     temp[totalLen]='\0';
     return temp;
 }
 
 // changes current string, returns nothing
 void String::operator+=(const String& rhs)
 {
     int rhsLen = rhs.GetLen();
     int totalLen = itsLen + rhsLen;
     String  temp(totalLen);
     int i,j;
     for ( i = 0; i<itsLen; i++)
         temp[i] = itsString[i];
     for ( j = 0; j<rhs.GetLen(); j++, i++)
         temp[i] = rhs[i-itsLen];
     temp[totalLen]='\0';
     *this = temp;
 }
 
 // int String::ConstructorCount = 0;
 
 std::ostream& operator<<( 
                          std::ostream& theStream,
                         String& theString)
 {
     theStream << theString.GetString();
     return theStream;
 }
 
 class pAddress
 {
 public:
     pAddress(SERVICE theService,
             const String& theAddress,
             const String& theDisplay):
         itsService(theService),
         itsAddressString(theAddress),
         itsDisplayString(theDisplay)
     {}
     // pAddress(String, String);
     // pAddress();
     // pAddress (const pAddress&);
     ~pAddress(){}
     friend std::ostream& operator<<( 
 	  std::ostream& theStream, pAddress& theAddress);
     String& GetDisplayString() 
 	{ return itsDisplayString; }
 private:
     SERVICE itsService;
     String itsAddressString;
     String itsDisplayString;
 };
 
 std::ostream& operator<<
   ( std::ostream& theStream, pAddress& theAddress)
 {
     theStream << theAddress.GetDisplayString();
     return theStream;
 }
 
 class PostMasterMessage
 {
 public:
 //  PostMasterMessage();
 
     PostMasterMessage(const pAddress& Sender,
                       const pAddress& Recipient,
                       const String& Subject,
                       const pDate& creationDate);
 
     ~PostMasterMessage(){}
 
     void Edit(); // invokes editor on this message
 
     pAddress& GetSender()  { return itsSender; }
     pAddress& GetRecipient()  { return itsRecipient; }
     String& GetSubject()  { return itsSubject; }
     //  void SetSender(pAddress& );
     // other member accessors
 
     // operator methods here, including operator equals
     // and conversion routines to turn PostMaster messages
     // into messages of other formats.
 
 private:
     pAddress itsSender;
     pAddress itsRecipient;
     String  itsSubject;
     pDate itsCreationDate;
     pDate itsLastModDate;
     pDate itsReceiptDate;
     pDate itsFirstReadDate;
     pDate itsLastReadDate;
 };
 
 PostMasterMessage::PostMasterMessage(
     const pAddress& Sender,
     const pAddress& Recipient,
     const String& Subject,
     const pDate& creationDate):
     itsSender(Sender),
     itsRecipient(Recipient),
     itsSubject(Subject),
     itsCreationDate(creationDate),
     itsLastModDate(creationDate),
     itsFirstReadDate(0),
     itsLastReadDate(0)
 {
     std::cout << "Post Master Message created. \n";
 }
 
 void PostMasterMessage::Edit()
 {
     std::cout << "PostMasterMessage edit function called\n";
 }
 
 
 int main()
 {
     pAddress Sender(
         PostMaster, "jliberty@PostMaster", "Jesse Liberty");
     pAddress Recipient(
         PostMaster, "sliberty@PostMaster","Stacey Liberty");
     PostMasterMessage PostMasterMessage(
         Sender, Recipient, "Saying Hello", 0);
     std::cout << "Message review... \n";
     std::cout << "From:\t\t" 
         << PostMasterMessage.GetSender() << std::endl;
     std::cout << "To:\t\t" 
         << PostMasterMessage.GetRecipient() << std::endl;
     std::cout << "Subject:\t" 
         << PostMasterMessage.GetSubject() << std::endl;
     return 0;
 }