解:
#include <iostream.h> #include <string.h> class MyString { public: MyString(); MyString(const char *const); MyString(const MyString &); ~MyString(); char & operator[](unsigned short offset); char operator[](unsigned short offset) const; MyString operator+(const MyString&); void operator+=(const MyString&); MyString & operator= (const MyString &); unsigned short GetLen()const { return itsLen; } const char * GetMyString() const { return itsMyString; } private: MyString (unsigned short); // private constructor char * itsMyString; unsigned short itsLen; }; MyString::MyString() { itsMyString = new char[1]; itsMyString[0] = '\0'; itsLen=0; } MyString::MyString(unsigned short len) { itsMyString = new char[len+1]; for (unsigned short i = 0; i<=len; i++) itsMyString[i] = '\0'; itsLen=len; } MyString::MyString(const char * const cMyString) { itsLen = strlen(cMyString); itsMyString = new char[itsLen+1]; for (unsigned short i = 0; i<itsLen; i++) itsMyString[i] = cMyString[i]; itsMyString[itsLen]='\0'; } MyString::MyString (const MyString & rhs) { itsLen=rhs.GetLen(); itsMyString = new char[itsLen+1]; for (unsigned short i = 0; i<itsLen;i++) itsMyString[i] = rhs[i]; itsMyString[itsLen] = '\0'; } MyString::~MyString () { delete [] itsMyString; itsLen = 0; } MyString& MyString::operator=(const MyString & rhs) { if (this == &rhs) return *this; delete [] itsMyString; itsLen=rhs.GetLen(); itsMyString = new char[itsLen+1]; for (unsigned short i = 0; i<itsLen;i++) itsMyString[i] = rhs[i]; itsMyString[itsLen] = '\0'; return *this; } char & MyString::operator[](unsigned short offset) { if (offset > itsLen) return itsMyString[itsLen-1]; else return itsMyString[offset]; } char MyString::operator[](unsigned short offset) const { if (offset > itsLen) return itsMyString[itsLen-1]; else return itsMyString[offset]; } MyString MyString::operator+(const MyString& rhs) { unsigned short totalLen = itsLen + rhs.GetLen(); MyString temp(totalLen); for (unsigned short i = 0; i<itsLen; i++) temp[i] = itsMyString[i]; for (unsigned short j = 0; j<rhs.GetLen(); j++, i++) temp[i] = rhs[j]; temp[totalLen]='\0'; return temp; } void MyString::operator+=(const MyString& rhs) { unsigned short rhsLen = rhs.GetLen(); unsigned short totalLen = itsLen + rhsLen; MyString temp(totalLen); for (unsigned short i = 0; i<itsLen; i++) temp[i] = itsMyString[i]; for (unsigned short j = 0; j<rhs.GetLen(); j++, i++) temp[i] = rhs[i-itsLen]; temp[totalLen]='\0'; *this = temp; } int main() { MyString s1("initial test"); cout << "S1:\t" << s1.GetMyString() << endl; char * temp = "Hello World"; s1 = temp; cout << "S1:\t" << s1.GetMyString() << endl; char tempTwo[20]; strcpy(tempTwo,"; nice to be here!"); s1 += tempTwo; cout << "tempTwo:\t" << tempTwo << endl; cout << "S1:\t" << s1.GetMyString() << endl; cout << "S1[4]:\t" << s1[4] << endl; s1[4]='x'; cout << "S1:\t" << s1.GetMyString() << endl; cout << "S1[999]:\t" << s1[999] << endl; MyString s2(" Another myString"); MyString s3; s3 = s1+s2; cout << "S3:\t" << s3.GetMyString() << endl; MyString s4; s4 = "Why does this work?"; cout << "S4:\t" << s4.GetMyString() << endl; return 0; }
程序运行输出:
S1: initial test
S1: Hello World
tempTwo: ; nice to be here!
S1: Hello World; nice to be here!
S1[4]: o
S1: Hellx World; nice to be here!
S1[999]: !
S3: Hellx World; nice to be here! Another myString
S4: Why does this work?
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解:
程序运行输出:
S1: initial test
S1: Hello World
tempTwo: ; nice to be here!
S1: Hello World; nice to be here!
S1[4]: o
S1: Hellx World; nice to be here!
S1[999]: !
S3: Hellx World; nice to be here! Another myString
S4: Why does this work?