1.请写出下面这个类的方法代码(20分)

class String
{
public:String(char *pstr);~String();String(const String &src);String& operator=(const String &src);
private:char *_pstr;
};
String::String(char *pstr)
{if (pstr == NULL){_pstr = new char[1]();}else{_pstr = new char[strlen(pstr) + 1]();strcpy_s(_pstr, strlen(pstr) + 1, pstr);}
}
String::~String()
{delete[] _pstr;_pstr = NULL;
}
String::String(const String &src)
{_pstr = new char[strlen(src._pstr) + 1]();strcpy_s(_pstr, strlen(src._pstr) + 1, src._pstr);
}
String& String::operator=(const String &src)
{if (this != &src){delete[] _pstr;_pstr = new char[strlen(src._pstr) + 1]();strcpy_s(_pstr, src._pstr + 1, src._pstr);}return (*this);
}int main()
{return 0;
}

2.请实现带头结点的单链表(15分)

class Link
{
public:Link(); //构造函数~Link(); //析构函数void insertHead(int val); //头插法void insertTail(int val); //尾插法bool empty();void deleteNode(int val); //删除链表所有值为val的节点void Show();
private://局部类class Node{public:Node(int data = 0) :_data(data), _pnext(NULL){}int _data;Node *_pnext;};Node *_phead;//头指针  
};Link::Link()//构造函数
{_phead = new Node();
}
Link::~Link() //析构函数
{Node* pCur = _phead;Node* pNext;while (pCur != NULL){pNext = pCur->_pnext;delete pCur;pCur = pNext;}_phead = NULL;
}
void Link::insertHead(int val)//头插法
{Node* pnewnode = new Node(val);pnewnode->_pnext = _phead->_pnext;_phead->_pnext = pnewnode;
}
void Link::insertTail(int val) //尾插法
{Node* pnewnode = new Node(val);Node* ptail = _phead;while (ptail->_pnext != NULL){ptail = ptail->_pnext;}ptail->_pnext = pnewnode;
}bool Link::empty()
{return _phead->_pnext == NULL;
}
void Link::deleteNode(int val)//删除链表所有值为val的节点
{if (empty()){return;}Node* pfront = _phead;Node* pCur;while (pfront->_pnext != NULL){pCur = pfront->_pnext;if (pCur->_data == val){pfront->_pnext = pCur->_pnext;delete pCur;}else{pfront = pfront->_pnext;}}
}void Link::Show()
{Node* pCur = _phead->_pnext;while (pCur != NULL){std::cout << pCur->_data << " ";pCur = pCur->_pnext;}std::cout << std::endl;
}
int main()
{Link link;for (int i = 0; i < 5; i++){link.insertHead(i + 1);}link.Show();for (int i = 0; i < 5; i++){link.insertTail(i + 1);}link.Show();link.deleteNode(1);link.Show();link.deleteNode(5);link.Show();return 0;
}

3.请给出下面对象创建过程中涉及的方法打印(20分)

class Test
{
public:Test(int a = 5, int b = 5) :ma(a), mb(b){cout << "Test(int, int)" << endl;}~Test(){cout << "~Test()" << endl;}Test(const Test &src) :ma(src.ma), mb(src.mb){cout << "Test(const Test&)" << endl;}void operator=(const Test &src){ma = src.ma; mb = src.mb; cout << "operator=" << endl;}
private:int ma;int mb;
};
Test t1(10, 10); //1.构造+}后销毁（程序结束后销毁）
int main()
{Test t2(20, 20);//3.构造 Test t3 = t2;//4.拷贝构造static Test t4 = Test(30, 30);//5.构造 ，}后销毁（显示生成临时对象，产生了优化）t2 = Test(40, 40);//6.构造，赋值运算符的重载，析构（3个）t2 = (Test)(50, 50);//7.构造，赋值运算符的重载，析构（3个）//===》（Test）（50，50)逗号表达式50赋给ma，mb为5t2 = 60;//8.构造，赋值运算符的重载，析构（3个）Test *p1 = new Test(70, 70);//9.构造，*不生成临时对象Test *p2 = new Test[2];//（生成了两个）10.构造，构造（2个），不生成临时对象Test *p3 = &Test(80, 80);//11.构造，析构（*不提升生存周期，把临时对象的入口地址赋给p3）Test &p4 = Test(90, 90);//12.构造（&不生成临时对象）delete p1;//13.析构p1delete[]p2;//14.析构p2两个对象return 0;//15.析构p4，t3，t2}//16.析构t4，t5，t1
Test t5(100, 100);//2.构造，}

4.请写出下面程序运行时方法涉及的打印信息(10分)

class Test
{
public:Test(int a = 5) :ma(a){ cout << "Test(int)" << endl; }~Test(){ cout << "~Test()" << endl; }Test(const Test &src) :ma(src.ma){cout << "Test(const Test&)" << endl;}void operator=(const Test &src){ma = src.ma;cout << "operator=" << endl;}int GetValue(){ return ma; }
private:int ma;
};
Test GetTestObject(Test &t)
{int value = t.GetValue();Test tmp(value);//Test();return tmp;//Test(const Test&)
}//~Test();
int main()
{Test t1(20);//Test()Test t2;//Test();t2 = GetTestObject(t1);//operator =   ~Test();cout << t2.GetValue() << endl;//20return 0;//~Test() ~Test();
}

5.选题题(单选和多选)(一题5分)

5.1请选择下面哪些代码是错误的？A

5.2扩展题：请判断下面哪些代码是错误的？BCD__

6.请解释explicit，volatile，mutable三个关键字。(20分)

==explicit：禁止隐式生成临时对象 ==
==volatile ：禁止编译器优化 ==
==mutable：去除常性 ==

下图中：如果是多线程，可能会改变b的值，导致出错

/*
volatile  禁止编译器优化 不可控的因素多线程mutable去除常性智能指针
*/class Test
{
public:Test(int a, int b){ma = a;mb = b;}
public:mutable int ma;//去除常性int mb;
};int main()
{const Test test(10, 20);//常对象的成员变量不可以修改/*不得不修改常量*/test.ma = 100;test.mb = 200;return 0;
}//关于explicit：
class Test
{
public:explicit Test(int a):ma(a){}
private:int ma;
};/*有安全隐患存在编译按照推演来处理（可能和本身的要求不相符）不可控的因素explicit禁止隐式生成临时对象   
*/
int main()
{Test test(20);test = 30;//Test  =   (int ==> Test)  隐式生成临时对象return 0;
}