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C++ exam

Name:

1   Extern

The code below declares and defines variable x. True or False ?

extern int x;

2   Namespace

In namespace foo, the function bar can access the variable x also declared in namespace foo ? True or False ?

#include <iostream>

namespace foo
{
    void bar()
    {
        x++;
    }
    int x;
}

int main(int argc, char** argv)
{
    return 0;
}

3   References

What is the output of the following program ?

#include <iostream>
using namespace std;

void swap1( int  a, int  b ) { int c=a; a=b; b=c; }
void swap2( int *a, int *b ) { int c=*a; *a=*b; *b=c; }
void swap3( int &a, int &b ) { int &c=a; a=b; b=c; }

int main( int argc, char **argv )
{
    int a, b;

    a = 1; b = 2; swap1(a,b);
    cout << "a: " << a << ", " <<"b: " << b << endl;

    a = 1; b = 2; swap2(&a,&b);
    cout << "a: " << a << ", " <<"b: " << b << endl;

    a = 1; b = 2; swap3(a,b);
    cout << "a: " << a << ", " <<"b: " << b << endl;
}

4   Inheritance

What is the output of the program ?

#include <iostream>

struct A { unsigned int color; };
struct B : public A { };
struct C : public A { };
struct D : public B, public C { };

int main(int argc, char** argv)
{
   D d;
   d.color = 3;
   std::cout << d.color << std::endl;
   return 0;
}

5   Inheritance

How many times is "Hello World" printed by this program ?

#include <iostream>

struct A { A() {  std::cout << "Hello World" << std::endl; } };
struct A1 : public A { };
struct A2 : public A { };
struct A3 : public A { };
struct A4 : public A { };
struct B : public A1, public A2, public A3, public A4 { };

int main(int argc, char** argv)
{
    B b;
    return 0;
}

6   Initialization

What is the value of x, y & z ?

#include <iostream>

struct A
{
  A(int n) : x(n++), y(n++), z(n++) {}
  int x;
  int y;
  int z;
};

int main(int argc, char** argv)
{
  Foo f(3);

  std::cout << "x: " << f.x << std::endl;
  std::cout << "y: " << f.y << std::endl;
  std::cout << "z: " << f.z << std::endl;

  return 0;
}

7   Logic

What value gets printed by the program?

#include <iostream>

int main(int argc, char** argv)
{
  int x = 0;
  int y = 0;

  if (x++ && y++)
  {
    y += 2;
  }

  std::cout << x + y << std::endl;

  return 0;
}

8   Constructors

Which lines below should not compile ?

struct A
{
   A(int x) : n(x) {}
   int n;
};

int main(int argc, char** argv)
{
  A a1;
  A a2(2);
  A a3(a2);
  return 0;
}

9   Memory

Which of the following implementations of the reset function is best for initializing the array to all zero.

class foo{
public:
    foo(){
        reset();
    }
private:
    void reset(){

    // A // memset(x, 0, 50);
    // B // memset(x, 0, sizeof(x));
    // C // memset(x, 0, 50 * 4);
    // D // memset(x, 0, 50 * sizeof(x));
    }

    long x[50];
};

10   References

What is the output of the program ?

#include <iostream>

int main(int argc, char** argv)
{
  // assume address of x is 0x822222222
  int x = 3;

  int*& rpx = &x;

  std::cout << rpx << std::endl;

  return 0;
}

11   End