C++ Programming Questions and Answers – Header Files Usage

This section on C++ interview questions and answers focuses on “Header Files Usage”. One shall practice these interview questions to improve their C++ programming skills needed for various interviews (campus interviews, walkin interviews, company interviews), placements, entrance exams and other competitive exams. These questions can be attempted by anyone focusing on learning C++ programming language. They can be a beginner, fresher, engineering graduate or an experienced IT professional. Our C++ interview questions come with detailed explanation of the answers which helps in better understanding of C++ concepts.

Here is a listing of C++ interview questions on “Header Files Usage” along with answers, explanations and/or solutions:

1. What is the user-defined header file extension in c++?
a) cpp
b) h
c) hf
d) hg
View Answer

Answer: b
Explanation: .h extensions are used for user defined header files. To include a user defined header file one should use #include”name.h” i.e. enclosed within double quotes.

2. Which of the following keyword is used to declare the header file?
a) include
b) exclude
c) string
d) namespace
View Answer

Answer: a
Explanation: The include keyword is used to include all the required things to execute the given code in the program.

3. Identify the incorrect statement.
a) iostream is a standard header and iostream.h is a non-standard header
b) iostream is a non-standard header and iostream.h is a non-standard header
c) iostream is a standard header and iostream.h is a standard header
d) iostream is a non-standard header
View Answer

Answer: a
Explanation: The iostream.h is used in the older versions of c++ and iostream is evolved from it in the std namespace.
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4. What does a default header file contain?
a) prototype
b) implementation
c) declarations
d) pointing
View Answer

Answer: c
Explanation: In the header file, we define something that to be manipulated in the program.

5. What will be the output of the following C++ code?

  1.     #include <iostream>
  2.     using namespace std;
  3.     int main()
  4.     {
  5.         char name[30];
  6.         cout << "Enter name: ";
  7.         gets(name);
  8.         cout << "Name: ";
  9.         puts(name);
  10.         return 0;
  11.     }

a) jobsjobs
b) jobs
c) compile time error
d) program will not run
View Answer

Answer: c
Explanation: This program will run on older version of C++ with the inclusion of #include header file, but for on new compiler C++14 and above the gets is removed from the header file so it will not run on them even after inclusion of cstdio header file.
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6. setprecision requires which of the following header file?
a) stdlib.h
b) iomanip.h
c) console.h
d) conio.h
View Answer

Answer: b
Explanation: The iomanip header file is used to correct the precision of the values.

7. Which of the following header file does not exist?
a) <iostream>
b) <string>
c) <sstring>
d) <sstream>
View Answer

Answer: c
Explanation: There is no such header file <sstring> in C++.
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8. Which of the header file must be included to use stringstream?
a) <iostream>
b) <string>
c) <sstring>
d) <sstream>
View Answer

Answer: b
Explanation: stringstream is available under the header file <string> in C++.

9. Which of the following header files is required for creating and reading data files?
a) ofstream.h
b) fstream.h
c) ifstream.h
d) console.h
View Answer

Answer: b
Explanation: In this fstream.h header file is used for accessing the files only.

10. What will be the output of the following C++ code?

  1.     #include <iostream>
  2.     #include <stdarg.h>
  3.     using namespace std;
  4.     float avg( int Count, ... )
  5.     {
  6.         va_list Numbers;
  7.         va_start(Numbers, Count);
  8.         int Sum = 0;
  9.         for (int i = 0; i < Count; ++i)
  10.             Sum += va_arg(Numbers, int);
  11.         va_end(Numbers);
  12.         return (Sum/Count);
  13.     }
  14.     int main()
  15.     {
  16.         float Average = avg(10, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9);
  17.         cout << Average;
  18.         return 0;
  19.     }

a) 4
b) 5
c) 6
d) compile time error
View Answer

Answer: a
Explanation: In this program, we are finding the average of first 10 numbers using stdarg header file
Output:

$ g++ std.cpp
$ a.out
4

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

To practice all areas of C++ language, here is complete set of 1000+ Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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