Welcome to the C/C++ Quiz!

please write down your answers on a new white paper. You can use either Chinese or English.

A. Show me the code

1. Please create a "String" class to process char strings. This string class should satisfy the following requirements:

• It could be used as an original type like "int" to define variables and support assignment and copy.
• It could be used as the parameter type of a function and the return value type of a function.
• It could be used as the element type of the STL container, e.g., vector/list/deque.

In other words, your "String" class could be used in the following code and be complied successfully by a standard C++ compiler.

void foo(String x)
{
}
void bar(const String& x)
{
}
String baz()
{
  String ret("world");
  return ret;
}
int main()
{
  String s0;
  String s1("hello");
  String s2(s0);
  String s3 = s1;
  s2 = s1;
  foo(s1);
  bar(s1);
  foo("temporary");
  bar("temporary");
  String s4 = baz();
  std::vector<String> svec;
  svec.push_back(s0);
  svec.push_back(s1);
  svec.push_back(baz());
  svec.push_back("good job");
}

2. Imagine we have a single linked list, please write a function which could remove a specified node in the list.

• Please define the data structure for the list as you need.
• Pass the head pointer to the function.
• Pass the pointer to the node to be removed to the function. Remove the node in the list if it has the same pointer value.

B. Basic Part

1. What are wrong in the following code? Please point out.

void main()
{
  char a = 'a';
  int b = 0;
  int *pInt1 = &b;
  int c = *pInt1;
  pInt1 = (int*)(&a);
  int *pInt2 = pInt1 + 1;
  int d = *pInt2;
  void *pV = &a;
  pV++;
  char e = *pV;
}

2. What are wrong in the following code? Please provide your FIX.

Common.h

int var1;
void foo(int input)
{
  // some code
}

TestA.h

#include "Common.h"
#include "TestB.h"
class CTestA
{
  private:
    CTestB m_b;
};

TestB.h

#include "Common.h"
#include "TestA.h"
class CTestB
{
  private:
    CTestA m_a;
}

TestA.cpp

#include "TestA.h"
// some code

TestB.cpp

#include "TestB.h"
// some code

C. STL

1. Errors, inefficiency and potential bugs exsit in the following code, please point them out.

int foo(std::map<int, int>& mapIn, std::set<int>& setIn)
{
  std::vector<int> va(10);
  std::vector<int> vb;
  std::copy(va.begin(), va.end(), vb.begin());
  std::vector<int> vc(100);
  auto iter = va.begin() + 5;
  int varInt = *iter;
  va.push_back(vc.begin(), vc.end());
  varInt = *(++iter);
  if (mapIn[4] == 0)
  {
    // do something 
  }
  auto itVec = std::find(vc.begin(), vc.end(), 100);
  if (itVec != vc.end())
  {
    // do something
  }
  auto itSet = std::find(setIn.begin(), setIn.end(), 10);
  if (itSet == setIn.end())
  {
    // do something
  }
}

2. Please see the following code, TypeA could be either a function pointer or a functor, please try to provide the definition for TypeA in both function pointer way and functor way.

void foo(TypeA processor)
{
  int paraInt = 0;
  const char* pParaStr = "Test";
  int rtn = processor(paraInt, pParaStr);
}