自定义字符串类MyString的C++实现

///////////////////////////////////////////////////////////////// 自定义字符串类MyString///////////////////////////////////////////////////////////////////////////////#include <iostream>#include <cstring>#include <malloc.h>using namespace std ;// 声明class MyString ;// 声明ostream& operator << ( ostream& os , const MyString& str ) ;istream& operator >> ( istream& is , const MyString& str ) ;// define of classclass MyString{public:// 默认构造函数MyString( char* str = "" ) ;// 拷贝构造函数    MyString( const MyString& str ) ;// 重载赋值运算符MyString& operator = ( const MyString& str ) ;// 重载输入运算符friend istream& operator >> ( istream& is , const MyString& str ) ;// 重载输出运算符friend ostream& operator << ( ostream& os , const MyString& str ) ;// 重载等于运算符bool operator == ( const MyString& ) ;// 返回字符串的长度int length() const { return strlen( ch )  ; }// 重载+运算符MyString& operator + ( const MyString& str ) ;// 在字符串中查找某个字符char* findChar( char* start , char* last , char ch ) ;public:char ch[1000] ;} ;// implement of class // 默认构造函数MyString::MyString( char* str ) {int i = 0 ;while( str[i] != '\0' ){ch[i] = str[i] ;i++ ;}ch[i] = '\0' ;}// 拷贝构造函数MyString::MyString( const MyString& str ){int i = 0 ;while( str.ch[i] != '\0' ){ch[i] = str.ch[i] ;i++ ;}ch[i] = '\0' ;}// 重载赋值运算符MyString& MyString::operator = ( const MyString& str ){if( &str != this ){int i = 0 ;while( str.ch[i] != '\0' ){ch[i] = str.ch[i] ;i++ ;}ch[i] = '\0' ;}return *this ;}// 重载输出运算符ostream& operator << ( ostream& os , const MyString& str ){for( int i = 0 ; i < strlen( str.ch ) ; i++ ){os << str.ch[i] ; }return os ;}// 重载输入运算符istream& operator >> ( istream& is , MyString& str ){char c ;int i = 0 ;while( 1 ){is >> noskipws ;is >> c ;if( c == '\n' ){break ;}else{str.ch[i] = c ;i++ ;}}str.ch[i] = '\0' ;return is ;}// 重载等于运算符bool MyString::operator == ( const MyString& str ){bool is_OK = true ;if( strlen( this->ch ) == strlen( str.ch ) ){for( int i = 0 ; i < strlen( ch ) ; i++ ){if( ch[i] != str.ch[i] ){is_OK = false ;}}}else{return false ;}return is_OK ;}// 重载+运算符MyString& MyString::operator + ( const MyString& str ){int size = this->length() + str.length() ;char* s = ( char* )malloc( sizeof( char ) * size ) ;for( int i = 0 ; i < this->length() ; i++ ){s[i] = this->ch[i] ;}for( int j = 0 ; j < str.length() ; j++ ){s[i+j] = str.ch[j] ;}s[i+j] = '\0' ;   // 字符串结尾,必须要注意return MyString( s ) ;}// 返回指向要查找的字符的指针，找不到返回NULLchar* MyString::findChar( char* first , char* last , char ch ) {while( first != last && *first != ch ){++first ;}if( first == last ){return NULL ;}else{return first ;}}//测试程序int main(){MyString  str( "hello World!" ) ;cout << "str=" << str << endl ;cout << &str.ch ;cout << endl << endl  ;MyString str1( str ) ;cout << "str1= " << str1 << endl ;cout << &str1.ch ;cout << endl << endl  ;MyString str2 ;str2 = str ;    cout << "str2=" << str2 << endl ;cout << &str2.ch ;cout << endl << endl  ;MyString str3 , str4 ;cin >> str3 >> str4 ;if( str3 == str4 ){cout << "str3 == str4 " << endl ;}else{cout << "str3 != str4 " << endl ;}MyString str5 = str3 + str4 ;cout << "str5 = " << str5 << endl ;char ch ;cout << "输入要查找的字符:" ;cin >> ch ;char* pChar = str5.findChar( str5.ch , str5.ch + str5.length() , ch ) ;if( pChar != NULL ){cout << "查找到的字符为:" << *pChar << endl ;}else{cout << "未找到!" << endl ;}return 0 ;}