24小时攻克c++代码

// 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; }