Unspecified Number of Arguments - C++ Questions and Answers

This section on C++ Programming Multiple Choice Questions focuses on “Unspecified Number of Arguments”. One shall practice these 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++ questions comes with detailed explanation of the answers which helps in better understanding of C++ concepts.

Here is a listing of C++ Programming Questions & Answers focuses on “Unspecified Number of Arguments” along with answers, explanations and/or solutions:

1. Which header file is used to pass unknown number of arguments to function?
a) stdlib.h
b) string.h
c) stdarg.h
d) stdio.h
View Answer

Answer: c
Explanation: Because the cstdarg defines this header file to process the unknown number of arguments.

2. How can you access the arguments that are manipulated in the function?
a) va_list
b) arg_list
c) both va_list & arg_list
d) vg_list
View Answer

Answer: a
Explanation: va_list is provided by C++ to access manipulated arguments in function.

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

```
    #include <iostream>
```
```
    #include <stdarg.h>
```
```
    using namespace std;
```
```
    float avg( int Count, ... )
```
```
    {
```
```
        va_list Numbers;
```
```
        va_start(Numbers, Count);
```
```
        int Sum = 0;
```

        for (int i = 0; i < Count; ++i )

            Sum += va_arg(Numbers, int);

```
        va_end(Numbers);
```
```
        return (Sum/Count);
```
```
    }
```
```
    int main()
```
```
    {
```

        float Average = avg(10, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9);

        cout << "Average of first 10 whole numbers : " << Average;

```
        return 0;
```
```
    }
```

a) 4
b) 5
c) 6
d) 7
View Answer

Answer: a
Explanation: We are just calculating the average of these numbers using cstdarg.
Output:

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$ g++ uka.cpp
$ a.out
Average of first 10 whole numbers 4

4. What is the maximum number of arguments or parameters that can be present in one function call?
a) 64
b) 256
c) 255
d) 16
View Answer

Answer: b
Explanation: C++ allows maximum number of 256 arguments in a function call.

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

```
    #include <iostream>
```
```
    #include <stdarg.h>
```
```
    using namespace std;
```
```
    int add (int num, ...)
```
```
    {
```
```
        int sum = 0;
```
```
        va_list args;
```
```
        va_start (args,num);
```
```
        for (int i = 0; i < num; i++) 
```
```
        {
```

            int num = va_arg (args,int);

```
            sum += num;
```
```
        }
```
```
        va_end (args);
```
```
        return sum;
```
```
    }
```
```
    int main (void)
```
```
    {
```

        int total = add(8, 1, 2, -1, 4, 12, -2, 9, 7);

        cout << "The result is " << total;

```
        return 0;
```
```
    }
```

a) 32
b) 23
c) 48
d) compile time error
View Answer

Answer: a
Explanation: We are adding these numbers by using for statement and stdarg.
Output:

$ g++ uka.cpp
$ a.out
The result is 32

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

```
    #include <iostream>
```
```
    #include <stdarg.h>
```
```
    using namespace std;
```
```
    void dumplist(int, ...);
```
```
    int main()
```
```
    {
```
```
        dumplist(2, 4, 8);
```
```
        dumplist(3, 6, 9, 7);
```
```
        return 0;
```
```
    }
```
```
    void dumplist(int n, ...)
```
```
    {
```
```
        va_list p;
```
```
        int i;
```
```
        va_start(p, n);
```
```
        while (n-->0) 
```
```
        {
```
```
            i = va_arg(p, int);
```
```
            cout << i;
```
```
        }
```
```
        va_end(p);
```
```
    }
```

a) 2436
b) 48697
c) 1111111
d) compile time error
View Answer

Answer: b
Explanation: In this program, we are eradicating the first value
by comparing using while operator.
Output:

$ g++ rka3.cpp
$ a.out
48697

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

```
    #include <iostream>
```
```
    #include <stdarg.h>
```
```
    using namespace std;
```
```
    int flue(char c,...);
```
```
    int main()
```
```
    {
```
```
        int x, y;
```
```
        x = flue('A', 1, 2, 3);
```

        y = flue('1', 1.0,1, '1', 1.0f, 1l);

```
        cout << x << y;
```
```
        return 0;
```
```
    }
```
```
    int flue(char c,...)
```
```
    {
```
```
        return c;
```
```
    }
```

a) 6549
b) 4965
c) 6646
d) compile time error
View Answer

Answer: a
Explanation: In this program, we are returning the ascii value of the character and printing it.
Output:

$ g++ rka4.cpp
$ a.out
6549

8. Which of the header file should be added in the following C++ code to properly run the program?

```
    #include <iostream>
```
```
    using namespace std;
```
```
    int print_all (int num, ...)
```
```
    {
```
```
        int sum = 0;
```
```
        va_list args;
```
```
        va_start (args,num);
```
```
        for (int i = 0; i < num; i++) 
```
```
        {
```

            int num = va_arg (args,int);

```
            cout<<num<<" ";
```
```
        }
```
```
        va_end (args);
```
```
        return sum;
```
```
    }
```
```
    int main (void)
```
```
    {
```

        print_all(8, 1, 2, -1, 4, 12, -2, 9, 7);

```
        return 0;
```
```
    }
```

a) stdlib.h
b) stdarg.h
c) string.h
d) stdpar.h
View Answer

Answer: b
Explanation: <stdarg.h> header provided to perform variable number of argument passing.

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

```
    #include <iostream>
```
```
    #include <stdarg.h>
```
```
    using namespace std;
```
```
    void fun(std::string msg, ...);
```
```
    int main()
```
```
    {
```

        fun("IndiaBIX", 1, 4, 7, 11, 0);

```
        return 0;
```
```
    }
```
```
    void fun(std::string msg, ...)
```
```
    {
```
```
        va_list ptr;
```
```
        int num;
```
```
        va_start(ptr, msg);
```
```
        num = va_arg(ptr, int);
```
```
        num = va_arg(ptr, int);
```
```
        cout << num;
```
```
    }
```

a) 6
b) 5
c) 8
d) 4
View Answer

Answer: d
Explanation: In this program, we are moving the pointer to the second value and printing it.
Output:

$ g++ uka6.cpp
$ a.out
4

10. What will initialize the list of arguments in stdarg.h header file?
a) va_list
b) va_start
c) va_arg
d) vg_arg
View Answer

Answer: b
Explanation: va_start initialises the the list of arguments in <stdarg.h> header file.

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