String& string operator=( String ob)i /赋值:从已有串ob复制 if(&ob!= this )i delete ch ch= new char[ maxlen+1l;/重新分配 if ( ch==NULL) cerr<<“ 内存不足m”;ext(1);} curlen=ob curLen: /复制 strcpy( ch, ob. ch ) else cout<<“字符串自身赋值出错!in”; return * thiString& String :: operator = ( String& ob ) { //串赋值：从已有串ob复制 if ( &ob != this ) { delete [ ] ch; ch = new char [maxLen+1]; //重新分配 if ( ch == NULL ) { cerr << “内存不足!\n ”; exit (1);} curLen = ob.curLen; //串复制 strcpy ( ch, ob.ch ); } else cout << “字符串自身赋值出错! \n”; return *this; }