Here is a listing of C++ interview questions on “Complex Number Type” along with answers, explanations and/or solutions:

1. Which header file is used to declare the complex number?

a) complexnum

b) complex

c) complex number

d) none of the mentioned

View Answer

Explanation: None.

2. How to declare the complex number?

a) (3,4)

b) complex(3,4)

c) (3,4i)

d) none of the mentioned

View Answer

Explanation: We can declare the complex number by using complex(3,4) where 3 is a real number and 4 is imaginary part.

3. How many real types are there in complex numbers?

a) 1

b) 2

c) 3

d) 4

View Answer

Explanation: There are three real types in complex numbers. They are float complex, double complex, long double complex.

4. What is the output of this program?

`#include <iostream>`

`#include <complex>`

using namespace std;

int main()

`{`

complex<double> c1(4.0, 16.0), c2;

c2 = pow(c1, 2.0);

cout << c2;

return 0;

`}`

a) (-240, 128)

b) (240, 128)

c) (240, 120)

d) None of the mentioned

View Answer

Explanation: In this program, we are finding the square of the complex number.

Output:

$ g++ comp.cpp $ a.out (-240,128)

5. What is the output of this program?

`#include <iostream>`

`#include <complex>`

using namespace std;

int main()

`{`

complex<double> c_double(2, 3);

complex<int> c_int(4, 5);

c_double *= 2;

c_double = c_int;

cout << c_double;

return 0;

`}`

a) (2, 3)

b) (4, 5)

c) (8, 15)

d) None of the mentioned

View Answer

Explanation: We are just copying the value of c_int into c_double, So it’s printing as (4,5).

Output:

$ g++ comp1.cpp $ a.out (4,5)

6. What is the output of this program?

`#include <iostream>`

`#include <complex>`

using namespace std;

int main()

`{`

complex<int> i(2, 3);

i = i * 6 / 3;

cout << i;

return 0;

`}`

a) (4, 6)

b) (2, 3)

c) (6, 12)

d) None of the mentioned

View Answer

Explanation: We are multiplying the complex number by 2.

Output:

$ g++ comp2.cpp $ a.out (4,6)

7. What is the output of this program?

`#include <iostream>`

`#include <complex>`

using namespace std;

int main()

`{`

complex<double> c1(4.0,3.0);

cout << "c1: " << c1;

complex<float> c2(polar(5.0,0.75));

cout << c1 + complex<double>(c2.real(),c2.imag());

return 0;

`}`

a) c1: (4,3)(7.65844,6.40819)

b) c1: (4,3)(7,6)

c) both c1: (4,3)(7.65844,6.40819) & c1: (4,3)(7,6)

d) None of the mentioned

View Answer

Explanation: We are adding the two complex numbers and printing the result.

Output:

$ g++ comp3.cpp $ a.out c1: (4,3)(7.65844,6.40819)

8. What is the output of this program?

`#include <iostream>`

`#include <complex>`

using namespace std;

int main()

`{`

complex<double> c1(4.0, 3.0);

complex<float> c2(polar(5.0, 0.75));

cout << (c1 += sqrt(c1)) << endl;

return 0;

`}`

a) (4.0, 3.0)

b) (6.12132, 3.70711)

c) (5.0, 0.75)

d) None of the mentioned

View Answer

Explanation: In this program, we are adding both complex number and finding the square root of it.

Output:

$ g++ comp4.cpp $ a.out (6.12132,3.70711)

9. Which of the following is not a function of complex values?

a) real

b) imag

c) norm

d) cartesian

View Answer

Explanation: None.

10. What is the output of this program?

`#include <iostream>`

`#include <complex>`

using namespace std;

int main ()

`{`

complex<double> mycomplex (20.0, 2.0);

cout << imag(mycomplex) << endl;

return 0;

`}`

a) 2

b) 20

c) 40

d) None of the mentioned

View Answer

Explanation: imag part will return the imaginary part of the complex number.

Output:

$ g++ comp5.cpp $ a.out 2

**Sanfoundry Global Education & Learning Series – C++ Programming Language.**