Common Coding Interview Questions For .NET Interview

This article explains commonly asked technical questions during interviews for entry level jobs (or sometimes even for an experienced person).

This article explains commonly asked coding example questions in technical rounds for .NET interviews. Here, I have given some examples with the code to help the developers prepare for a technical interview. It looks simple but during the interview, it will be difficult to explain or write on paper.
 
I have attached the source code with this article for all the below examples.
 

Common programs to build that interviewers ask during .NET interviews

  1. static void Main(string[] args)    
  2. {    
  3.             //Write Program to find fibonacci series for given number    
  4.             for (int i = 0; i < 10; i++)    
  5.             {    
  6.                 Console.Write("{0} ", FibbonacciSeries(i));    
  7.             }    
  8.             Console.WriteLine(Environment.NewLine);    
  9.     
  10.             Console.Write("Fibbonacci Series of {0} is : {1} ", 10, FibbonacciSeries1(10));    
  11.     
  12.             Console.WriteLine(Environment.NewLine);    
  13.     
  14.             //Write Program to calculate factorial value for given number    
  15.             Console.WriteLine("The Factorial of {0} is: {1} \n", 6, Factorial(6));    
  16.     
  17.             //Write Program to find duplicate in String    
  18.             FindDuplicateCharacterInString("CSharpCorner");    
  19.     
  20.             Console.WriteLine(Environment.NewLine);    
  21.             //Write Program to find duplicate in string array    
  22.             FindDuplicateInstringArray();    
  23.     
  24.             Console.WriteLine(Environment.NewLine);    
  25.             //Write Program to Remove duplicate in string    
  26.             RemoveDuplicate("CSharpCorner");    
  27.     
  28.             Console.WriteLine(Environment.NewLine);    
  29.             //Write Program to find number of character in string    
  30.             FindNumberofCharaterinString();    
  31.     
  32.             Console.WriteLine(Environment.NewLine);    
  33.             //Write Program to find number of words in string    
  34.             ReverseStringWords("Jignesh Kumar");    
  35.     
  36.             Console.WriteLine(Environment.NewLine);    
  37.             //Write Program to find consicutive character in string    
  38.             char[] charArray = { 'A''B''B''C''D''D''E''F''F' };    
  39.             FindConsicutiveCharacter(charArray);    
  40.     
  41.             Console.WriteLine(Environment.NewLine);    
  42.             //Write Program to check string is palindrome or not    
  43.             string[] strArray = { "WOW""NOON""ABBA""ANNA""BOB""Jimmy""Peter" };    
  44.     
  45.             foreach (var item in strArray)    
  46.             {    
  47.                 Console.WriteLine(" {0} Is palindrome {1}", item, IsStringPalindrome(item));    
  48.             }    
  49.     
  50.             Console.WriteLine(Environment.NewLine);    
  51.             //Write program to check number is palindrome or not    
  52.             int number = 121;    
  53.             Console.WriteLine("{0} is Palindrome number {1} ", number, IsNumberPalindrome(number));    
  54.     
  55.             Console.WriteLine(Environment.NewLine);    
  56.             //Write program to check number is palindrome or not    
  57.             number = 127;    
  58.             Console.WriteLine("{0} is prime number {1} ", number, IsNumberPrime(number));    
  59.             number = 128;    
  60.             Console.WriteLine("{0} is prime number {1} ", number, IsNumberPrime(number));    
  61.             Console.ReadLine();    
  62. }   

Write a program for printing a fibonacci series for a given number

  1. private static int FibbonacciSeries(int number)    
  2. {    
  3.            int firstValue = 0;    
  4.            int secondValue = 1;    
  5.            int result = 0;    
  6.            if (number == 0)    
  7.                return 0;    
  8.            if (number == 1)    
  9.                return 1;    
  10.            for (int i = 2; i <= number; i++)    
  11.            {    
  12.                result = firstValue + secondValue;    
  13.                firstValue = secondValue;    
  14.                secondValue = result;    
  15.            }    
  16.            return result;    
  17.  }    
  18.     
  19. public static string FibbonacciSeries1(int n)    
  20. {    
  21.            int a = 0, b = 1, c;    
  22.            StringBuilder sb = new StringBuilder();    
  23.            for (int i = 1; i < n; i++)    
  24.            {    
  25.                sb.Append(a.ToString() + ",");    
  26.                c = a + b;    
  27.                a = b;    
  28.                b = c;    
  29.            }    
  30.            return sb.ToString().Remove(sb.Length - 1); ;    
  31. }  

Write a program to calculate factorial value for a given number

  1. private static int Factorial(int number)    
  2. {    
  3.            int fact = 1;    
  4.            if (number == 0)    
  5.                return 0;    
  6.            if (number == 1)    
  7.                return 1;    
  8.     
  9.            for (int i = 1; i <= number; i++)    
  10.            {    
  11.                fact = fact * i;    
  12.            }    
  13.            return fact;    
  14. }   

Write a program to find duplicate in String

  1. private static void FindDuplicateCharacterInString(string inPutString)    
  2. {    
  3.     
  4.             if (string.IsNullOrEmpty(inPutString))    
  5.             {    
  6.                 Console.WriteLine("Please enter valid Input");    
  7.             }    
  8.             else    
  9.             {    
  10.                 var list = new List<char>();    
  11.                 string result = string.Empty;    
  12.     
  13.                 foreach (char item in inPutString)    
  14.                 {    
  15.                     if (list.Contains(item))    
  16.                     {    
  17.                         if (!result.Contains(item))    
  18.                             result += item;    
  19.                     }    
  20.                     else    
  21.                     {    
  22.                         list.Add(item);    
  23.                     }    
  24.                 }    
  25.                 Console.WriteLine("Duplicate Found : {0} ", result);    
  26.             }      
  27. }  

Write a program to find duplicate in a string array

  1. public static void FindDuplicateInstringArray()    
  2. {    
  3.             string[] strArray = { "Sunday""Monday""Tuesday""Wednesday""Sunday""Monday" };    
  4.             List<string> lstString = new List<string>();    
  5.             StringBuilder sb = new StringBuilder();    
  6.     
  7.             foreach (var str in strArray)    
  8.             {    
  9.                 if (lstString.Contains(str))    
  10.                 {    
  11.                     sb.Append(" " + str);    
  12.     
  13.                 }    
  14.                 else    
  15.                 {    
  16.                     lstString.Add(str);    
  17.                 }    
  18.             }    
  19.             Console.WriteLine("Duplicate Found : {0}", sb.ToString());    
  20. }   
Write a program to remove duplicate in string:
  1. public static void RemoveDuplicate(string inputString)    
  2. {    
  3.             var list = new List<char>();    
  4.     
  5.             foreach (var item in inputString)    
  6.             {    
  7.                 if (!list.Contains(item))    
  8.                 {    
  9.                     list.Add(item);    
  10.                 }    
  11.             }    
  12.     
  13.       Console.WriteLine("Orignal String {0}, After duplicate removed {1}", inputString, new string(list.ToArray()));    
  14. }   

Write a program to find a number of character in a string

  1. public static void FindNumberofCharaterinString()    
  2. {    
  3.             string StringToCount = "DotNetDeveloper";    
  4.             var result = FindOccuranceofCharacterInString(StringToCount);    
  5.     
  6.             Console.WriteLine("Number of occurrences of a character in given string");    
  7.             foreach (var count in result)    
  8.             {    
  9.                 Console.WriteLine(" {0} - {1} ", count.Key, count.Value);    
  10.             }    
  11. }    
  12.     
  13. public static SortedDictionary<charint> FindOccuranceofCharacterInString(string str)    
  14. {    
  15.  SortedDictionary<charint> count = new SortedDictionary<charint>();    
  16.     
  17.             foreach (var chr in str)    
  18.             {    
  19.                 if (!(count.ContainsKey(chr)))    
  20.                 {    
  21.                     count.Add(chr, 1);    
  22.                 }    
  23.                 else    
  24.                 {    
  25.                     count[chr]++;    
  26.                 }    
  27.             }    
  28.     
  29.     return count;    
  30. }    

Write a program to find a number of words in a string

  1. public static void ReverseStringWords(string inputString)    
  2. {    
  3.             string[] seprator = { " " };    
  4.             string[] words = inputString.Split(seprator, StringSplitOptions.RemoveEmptyEntries);    
  5.             string result = string.Empty;    
  6.             for (int i = words.Length - 1; i >= 0; i--)    
  7.             {    
  8.                 result += words[i].ToString();    
  9.             }    
  10.      Console.WriteLine("Reverse words in string {0}", result);    
  11. }    

Write a program to find the consecutive characters in a string

  1. public static void FindConsicutiveCharacter(char[] characterArray)    
  2. {    
  3.            int len = characterArray.Length - 1;    
  4.            List<char> result = new List<char>();    
  5.            for (int i = 0; i < len; i++)    
  6.            {    
  7.                for (int j = i + 1; j <= len; j++)    
  8.                {    
  9.                    if (characterArray[i] == characterArray[j])    
  10.                    {    
  11.                        if (!result.Contains(characterArray[i]))    
  12.                            result.Add(characterArray[i]);    
  13.                        continue;    
  14.                    }    
  15.                    else    
  16.                    {    
  17.                        break;    
  18.                    }    
  19.                }    
  20.            }    
  21.     
  22.            Console.WriteLine("Consicutive Character found {0} "new string(result.ToArray()));    
  23. }    

Write a program to check if a string/number is a palindrome or not

  1. public static bool IsStringPalindrome(string inputString)    
  2. {    
  3.             int minIdex = 0;    
  4.             int maxIdex = inputString.Length - 1;    
  5.             while (true)    
  6.             {    
  7.                 if (minIdex > maxIdex)    
  8.                 {    
  9.                     return true;    
  10.                 }    
  11.                 char charfromLeft = inputString[minIdex];    
  12.                 char charfromRight = inputString[maxIdex];    
  13.                 if (charfromLeft != charfromRight)    
  14.                 {    
  15.                     return false;    
  16.                 }    
  17.                 minIdex++;    
  18.                 maxIdex--;    
  19.             }      
  20. }      
  21. public static bool IsNumberPalindrome(int number)    
  22. {    
  23.             int reminder, sum = 0;    
  24.             int tempNumber;    
  25.             tempNumber = number;    
  26.             bool IsPalindrome = false;    
  27.             while (number > 0)    
  28.             {    
  29.                 reminder = number % 10;    
  30.                 number = number / 10;    
  31.                 sum = sum * 10 + reminder;    
  32.                 if (tempNumber == sum)    
  33.                 {    
  34.                     IsPalindrome = true;    
  35.                 }    
  36.             }    
  37.             return IsPalindrome;    
  38. }    

Write a program to check if a number is prime or not

  1. public static bool IsNumberPrime(int number)    
  2. {    
  3.             int i;    
  4.             for (i = 2; i <= number - 1; i++)    
  5.             {    
  6.                 if (number % i == 0)    
  7.                 {    
  8.                     return false;    
  9.                 }    
  10.             }    
  11.             if (i == number)    
  12.             {    
  13.                 return true;    
  14.             }    
  15.             return false;    
  16. }   
 
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