C/C++ Quiz

For your answers, either Chinese or English are OK.

A. Coding

1. Please create a class to represent Int. Only declaration is required. Please give the declaration of all member functions, friend functions, and member variables.

2. Imagine we have a single linked list, please write a function which could move a specified node to the tail of the list.

• Please define the data structure for the list as you need.
• Pass the head pointer to the function.
• Pass the pointer of the node to be moved to the function. Move the node to the tail of the list if it has the same pointer value.

B. Read and Answer

1. What are wrong in the following code?

void foo(short startIndex)
{
  short buffer[50000] = { 0 };
  for (auto i = startIndex; i < 40000; ++i)
  {
    buffer[i] = (char)i;
  }

2. Mark all lines which are wrong and provide the FIX.

class CBase
{
public:
    CBase() 
      : m_pVar1(NULL)
    {
        m_pVar2 = new int(4);
    }
    ~CBase()
    {
        delete m_pVar2;
        delete m_pVar1;
    }
    void Init(int* pVar)
    {
        m_pVar1 = pVar;
    }
private:
    int* m_pVar1;
    int* m_pVar2;
}
class CDerive : public CBase
{
public:
    CDerive(int var) : m_var(var) {};
    ~CDerive() {};
private:
    int m_var;
}
int main()
{
    CDerive* pDerives = new CDerive[10];
    int *pVar = new int(10);
    for (int i = 0; i < 10; ++i)
    {
        pDerive[i].Init(pVar);
    }
    delete pDerives;
    delete pVar;
}

3. The following code could not be compiled, give TWO ways to fix it.

class CFoo
{
public:
    CFoo() : m_var(0) {};
    ~CFoo() {};
    bool AddAndCheck() const
    {
        m_var += 5;
        return m_var < 10;
    }
private:
    int m_var;
}

4. What are wrong in the following code? Provide your fix.

#define INCREASE(a) ++a 
void foo()
{
    int a = 3;
    int b = 7;
    cout<<INCREASE(a * b)<<endl;
}

5. What are wrong in the following code? Why?

char* GetStaticBuffer()
{
    char buffer[100] = { 0 };
    return buffer;
}

6. With default configuration, in the following code, function fooA is OK but fooB has issues, why?

const int TEN_MEGA_BYTES = 10 * 1024 * 1024;
void fooA()
{
    char *pBuffer = new char[TEN_MEGA_BYTES];
}
void fooB()
{
    char buffer[TEN_MEGA_BYTES] = { 0 };
}

7. In the following code, line 32, I want to give "student_teacher" as the input parameter, but by mistake, I typed "student". The compiling succeeded anyway. Why? If I want the compiling be failed in this condition, how to do?

class CStudent
{
public:
    CStudent() {};
    ~CStudent() {};
}
class CTeacher
{
public:
    CTeacher(CStudent student) {};
    CTeacher(CStudent student)
        : m_student(student)
    {
    }
    ~CTeacher() {};
    void Teach() {};
private:
    CStudent m_student;
}
void foo(CTeacher teacher)
{
    teacher.Teach();
}
int main()
{
    CStudent student;
    CTeacher student_teacher;
    foo(student);
}

8. What is the output of the following code?

int fooVar = 10;
void foo(int *pVar, int& var)
{
    pVar = &fooVar;
    var = fooVar;
}
int main()
{
    int var1 = 1;
    int var2 = 2;
    foo(&var1, var2);
    cout<<var1<<":"<<var2<<endl;
}

9. How to run some code before main function is called?

10. What the difference are between

std::vector::resize() and std::vector::reserve()
std::vector::size() and std::vector::capacity()

11. Template greater<> is often used when operating the STL containers. Please give an implementation of greater<>.

Hints: Two template parameters. One is a number to be compared as base, another is the element to be compared.

12. Say we have a class named Printer which has a member function as Print(). Now there's a container as vector. Please give a lambda expression which could be used in for_each() to call Print() function for every instance in vector.