东南大学机试-B卷-答案.doc

东南大学09级C++（下）上机试卷B-答案 一、改错题（50分）本题共10个错误，每个错误5分 #include iostream #include cstring using namespace std; class student { char *pName; public: student(); student(char *pname); student(student s); ~student(); student operator=(student s); void print(); }; student::student() //去掉void { coutConstructor; pName=NULL; cout缺省endl; } student::student ( char *pname ) { coutConstructor; pName = new char[strlen(pname)]; if ( pName ) strcpy ( pName, pname); //pName与pname互换位置 coutpNameendl; } student::student(student s) //改为student s { coutCopy Constructor; if(s.pName) { int len = strlen( s.pName ); pName = new char[len+1]; //len改为len+1 if ( pName ) strcpy (pName, s.pName); coutpNameendl; } else pName=NULL; } student::~student() { coutDestructor; if ( pName ) coutpNameendl; delete pName; //改为delete pName; } student student::operator = ( student s ) { coutCopy Assign operator; delete[] pName; if ( s.pName ) { pName = new char[strlen(s.pName)+1]; if ( pName ) strcpy ( pName, s.pName ); coutpNameendl; } else pName=NULL; return *this; //改为return *this; } void student::print( ) //改为void student::print( ) { if (pName = NULL ) cout NULL endl; else cout pName endl; } void main(void) { student s1(范英明),s2(沈俊); student *s3 = new student; *s3 = s1; //改为*s3 = s1; s1.print(); s2.print(); s3-print(); //改为s3-print(); delete s3; return; //去掉0 } 二、编程题（50分）每段代码10分，共50分。红字为要求设计的部分。 #include iostream #include fstream #include string using namespace std; class goods; ostream operator(ostream os, goods a); istream operator(istream is, goods a); class goods { string Name; //名称 int Amount; //数量 float Price; //单价 public: goods (); ~ goods (); //析构函数，将数据保存到文件中 bool IsEmpty(){ return Name==; }; friend ostream operator(ostream os, goods a); //用于直接输出数组对象 friend istream operator(istream is, goods a); }; goods:: goods () { ifstream file(goodinfo.data); if