Recursion - C# Questions & Answers

This section of our 1000+ C# multiple choice questions focuses on recursion of C# Programming Language.

1. What is Recursion in CSharp defined as?
a) Recursion is another form of class
b) Recursion is another process of defining a method that calls other methods repeatedly
c) Recursion is a process of defining a method that calls itself repeatedly
d) Recursion is a process of defining a method that calls other methods which in turn calls this method
View Answer

Answer: c
Explanation: Recursion is the process of defining something in terms of itself. It allows us to define method that calls itself repeatedly until it meets some base case condition.

2. Which of these will happen if the recursive method does not have a base case?
a) Infinite loop condition occurrence
b) System gets hanged
c) After 10000 executions program will be automatically stopped
d) None of the mentioned
View Answer

Answer: a
Explanation: If a recursive method does not have a base case which is necessary to meet the end of condition then an infinite loop occurs which results in stackoverflow exception error.

3. Which of these is not a correct statement?
a) A recursive method must have a base case
b) Recursion always uses stack
c) Recursion is always managed by C# Runtime environment
d) Recursive methods are faster that programmer written loop to call the function repeatedly using a stack
View Answer

Answer: c
Explanation: No matter whatever is the programming language recursion is always managed by the operating system.

4. What will be the output of the following C# code?

```
 class recursion 
```
```
 {
```
```
     int fact(int n) 
```
```
     {
```
```
         int result;
```
```
         if (n == 1)
```
```
         return 1;
```
```
         result = fact(n - 1) * n;
```
```
         return result;
```
```
     }
```
```
 } 
```
```
 class Program 
```
```
 {
```

     public static void main(String args[])

```
     {
```

         recursion obj = new recursion() ;

         Console.WriteLine(obj.fact(4));

```
     }
```
```
 }
```

a) 24
b) 30
c) 120
d) 144
View Answer

Answer: a
Explanation: None.

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

```
 class maths 
```
```
 {
```
```
     int fact(int n) 
```
```
     {
```
```
         int result;
```
```
         if (n == 1)
```
```
         return 1;
```
```
         result = fact(n - 1) * n;
```
```
         return result;
```
```
     }
```
```
 } 
```
```
 class Output 
```
```
 {
```
```
     static void main(String args[]) 
```
```
     {
```
```
         maths obj = new maths() ;
```

         Console.WriteLine(obj.fact(1));

```
     }
```
```
 }
```

a) 2
b) 10
c) 1
d) 0
View Answer

Answer: c
Explanation: fact() calculates recursively the factorial of a number when n turns to be 1, base case is executed consecutively and hence 1 is returned.
Output: 1

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

```
class maths 
```
```
 {
```
```
     int fact(int n) 
```
```
     {
```
```
         int result;
```
```
         if (n == 1)
```
```
         return 1;
```
```
         result = fact(n - 1) * n;
```
```
         return result;
```
```
     }
```
```
 } 
```
```
 class Output 
```
```
 {
```
```
     static void main(String args[]) 
```
```
     {
```
```
         maths obj = new maths() ;
```

         Console.WriteLine(obj.fact(4)*obj.fact(2));

```
     }
```
```
 }
```

a) 64
b) 60
c) 120
d) 48
View Answer

Answer: d
Explanation: 4! = 4*3*2*1 & 2! = 2*1. So, 24*2 = 48.
Output : 48

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

```
 class maths 
```
```
 {
```
```
     int fact(int n) 
```
```
     {
```
```
         int result;
```
```
         if (n == 1)
```
```
         return 1;
```
```
         result = fact(n - 1) * n;
```
```
         return result;
```
```
     }
```
```
 } 
```
```
 class Output 
```
```
 {
```
```
     static void main(String args[]) 
```
```
     {
```
```
         maths obj = new maths() ;
```

         Console.WriteLine(obj.fact(4)*(3));

```
     }
```
```
 }
```

a) 64
b) 60
c) 72
d) 84
View Answer

Answer: c
Explanation: 4! = 4 * 3 *2 * 1 = 24 * 3 = 72. Not factorial of 3 but just multiply the number with 3.
Output : 72

8. Which of these data types is used by the operating system to manage the Recursion in Csharp?
a) Array
b) Queue
c) Tree
d) Stack
View Answer

Answer: d
Explanation: None.

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

```
 class maths
```
```
 {
```
```
     public int fact(int n)
```
```
     {
```
```
         int result;
```
```
         result = fact(n - 1) * n;
```
```
         return result;
```
```
     }
```
```
 } 
```
```
 class Program
```
```
 {
```
```
     static void Main(string[] args)
```
```
     {            
```
```
         maths obj = new maths();
```

         Console.WriteLine(obj.fact(4));

```
         Console.ReadLine();
```
```
     }
```
```
 }
```

a) 24
b) 30
c) Compile time error
d) Runtime Error
View Answer

Answer: d
Explanation: Absence of base case condition. So absence of limit or end of for execution of a loop and hence results in stackoverflow exception error.

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

```
 class maths
```
```
 {
```
```
     public int fact(int n)
```
```
     {
```
```
         int result;
```
```
         if (n == 2)
```
```
         return 1;
```
```
         result = fact(n - 1) * n;
```
```
         return result;
```
```
     }
```
```
 } 
```
```
 class Program
```
```
 {
```
```
     static void Main(string[] args)
```
```
     {            
```
```
         maths obj = new maths();
```

         Console.WriteLine(obj.fact(4));

```
         Console.ReadLine();
```
```
     }
```
```
 }
```

a) 24
b) 0
c) 12
d) 1
View Answer

Answer: c
Explanation: fact() calculates factorial of number ‘4’ but this time base case condition is executed upto 2 only. As soon as n reaches 2 it returns 2.

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