Question

c++ question

1. C++ string Class

What does the output look like after executing the following statements?

std::string numstr = "12";
numstr += "3";
std::cout << numstr << '\n';

A. None of these.

B. The snippet has syntax errors.

C. 15

D.123

//

2. Let S be a class that allows integers to be stored in its objects like an array. For example, if obj is an object of S, one can write statements like

obj[0] = 100;

or

int x = obj[0];

What is required in the class specification?

A. A public member function int operator[](int);

B. None of these

C. A public member function int[] S(int);

D. A public member function  int &operator[](int);

//

3. Given a class Coll and some variables as follows:

class Coll {};

Coll obj;

char *cPtr = nullptr;

Coll *ptr = &obj;

Which casting is allowed by C++?

A. cPtr = reinterpret_cast<char *>(ptr);

B. cPtr = dynamic_cast<char *>(ptr);

C. None of these.

D.cPtr = static_cast<char *>(ptr);

Answer 1

1.

std::string numstr = "12"; // Initially the string is 12
numstr += "3"; // String concatenate with one more character that is 3
std::cout << numstr << '\n'; // print 123

Option d

2.

Let S be a class that allows integers to be stored in its objects like an array. For example, if obj is an object of S, one can write statements like

A public member function  int &operator[](int);

Option d

3.

class Coll {};

Coll obj;

char *cPtr = nullptr;

Coll *ptr = &obj;

class Coll and some variables as follows cPtr = dynamic_cast<char *>(ptr);

Option b