Common Coding Interview Questions For .NET Interview

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

static void Main(string[] args)
{
//Write Program to find fibonacci series for given number
for (int i = 0; i < 10; i++)
{
Console.Write("{0} ", FibbonacciSeries(i));
}
Console.WriteLine(Environment.NewLine);
Console.Write("Fibbonacci Series of {0} is : {1} ", 10, FibbonacciSeries1(10));
Console.WriteLine(Environment.NewLine);
//Write Program to calculate factorial value for given number
Console.WriteLine("The Factorial of {0} is: {1} \n", 6, Factorial(6));
//Write Program to find duplicate in String
FindDuplicateCharacterInString("CSharpCorner");
Console.WriteLine(Environment.NewLine);
//Write Program to find duplicate in string array
FindDuplicateInstringArray();
Console.WriteLine(Environment.NewLine);
//Write Program to Remove duplicate in string
RemoveDuplicate("CSharpCorner");
Console.WriteLine(Environment.NewLine);
//Write Program to find number of character in string
FindNumberofCharaterinString();
Console.WriteLine(Environment.NewLine);
//Write Program to find number of words in string
ReverseStringWords("Jignesh Kumar");
Console.WriteLine(Environment.NewLine);
//Write Program to find consicutive character in string
char[] charArray = { 'A', 'B', 'B', 'C', 'D', 'D', 'E', 'F', 'F' };
FindConsicutiveCharacter(charArray);
Console.WriteLine(Environment.NewLine);
//Write Program to check string is palindrome or not
string[] strArray = { "WOW", "NOON", "ABBA", "ANNA", "BOB", "Jimmy", "Peter" };
foreach (var item in strArray)
{
Console.WriteLine(" {0} Is palindrome {1}", item, IsStringPalindrome(item));
}
Console.WriteLine(Environment.NewLine);
//Write program to check number is palindrome or not
int number = 121;
Console.WriteLine("{0} is Palindrome number {1} ", number, IsNumberPalindrome(number));
Console.WriteLine(Environment.NewLine);
//Write program to check number is palindrome or not
number = 127;
Console.WriteLine("{0} is prime number {1} ", number, IsNumberPrime(number));
number = 128;
Console.WriteLine("{0} is prime number {1} ", number, IsNumberPrime(number));
Console.ReadLine();
}

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

private static int FibbonacciSeries(int number)
{
int firstValue = 0;
int secondValue = 1;
int result = 0;
if (number == 0)
return 0;
if (number == 1)
return 1;
for (int i = 2; i <= number; i++)
{
result = firstValue + secondValue;
firstValue = secondValue;
secondValue = result;
}
return result;
}
public static string FibbonacciSeries1(int n)
{
int a = 0, b = 1, c;
StringBuilder sb = new StringBuilder();
for (int i = 1; i < n; i++)
{
sb.Append(a.ToString() + ",");
c = a + b;
a = b;
b = c;
}
return sb.ToString().Remove(sb.Length - 1); ;
}

Write a program to calculate factorial value for a given number

private static int Factorial(int number)
{
int fact = 1;
if (number == 0)
return 0;
if (number == 1)
return 1;
for (int i = 1; i <= number; i++)
{
fact = fact * i;
}
return fact;
}

Write a program to find duplicate in String

private static void FindDuplicateCharacterInString(string inPutString)
{
if (string.IsNullOrEmpty(inPutString))
{
Console.WriteLine("Please enter valid Input");
}
else
{
var list = new List<char>();
string result = string.Empty;
foreach (char item in inPutString)
{
if (list.Contains(item))
{
if (!result.Contains(item))
result += item;
}
else
{
list.Add(item);
}
}
Console.WriteLine("Duplicate Found : {0} ", result);
}
}

Write a program to find duplicate in a string array

public static void FindDuplicateInstringArray()
{
string[] strArray = { "Sunday", "Monday", "Tuesday", "Wednesday", "Sunday", "Monday" };
List<string> lstString = new List<string>();
StringBuilder sb = new StringBuilder();
foreach (var str in strArray)
{
if (lstString.Contains(str))
{
sb.Append(" " + str);
}
else
{
lstString.Add(str);
}
}
Console.WriteLine("Duplicate Found : {0}", sb.ToString());
}

Write a program to remove duplicate in string:

public static void RemoveDuplicate(string inputString)
{
var list = new List<char>();
foreach (var item in inputString)
{
if (!list.Contains(item))
{
list.Add(item);
}
}
Console.WriteLine("Orignal String {0}, After duplicate removed {1}", inputString, new string(list.ToArray()));
}

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

public static void FindNumberofCharaterinString()
{
string StringToCount = "DotNetDeveloper";
var result = FindOccuranceofCharacterInString(StringToCount);
Console.WriteLine("Number of occurrences of a character in given string");
foreach (var count in result)
{
Console.WriteLine(" {0} - {1} ", count.Key, count.Value);
}
}
public static SortedDictionary<char, int> FindOccuranceofCharacterInString(string str)
{
SortedDictionary<char, int> count = new SortedDictionary<char, int>();
foreach (var chr in str)
{
if (!(count.ContainsKey(chr)))
{
count.Add(chr, 1);
}
else
{
count[chr]++;
}
}
return count;
}

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

public static void ReverseStringWords(string inputString)
{
string[] seprator = { " " };
string[] words = inputString.Split(seprator, StringSplitOptions.RemoveEmptyEntries);
string result = string.Empty;
for (int i = words.Length - 1; i >= 0; i--)
{
result += words[i].ToString();
}
Console.WriteLine("Reverse words in string {0}", result);
}

Write a program to find the consecutive characters in a string

public static void FindConsicutiveCharacter(char[] characterArray)
{
int len = characterArray.Length - 1;
List<char> result = new List<char>();
for (int i = 0; i < len; i++)
{
for (int j = i + 1; j <= len; j++)
{
if (characterArray[i] == characterArray[j])
{
if (!result.Contains(characterArray[i]))
result.Add(characterArray[i]);
continue;
}
else
{
break;
}
}
}
Console.WriteLine("Consicutive Character found {0} ", new string(result.ToArray()));
}

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

public static bool IsStringPalindrome(string inputString)
{
int minIdex = 0;
int maxIdex = inputString.Length - 1;
while (true)
{
if (minIdex > maxIdex)
{
return true;
}
char charfromLeft = inputString[minIdex];
char charfromRight = inputString[maxIdex];
if (charfromLeft != charfromRight)
{
return false;
}
minIdex++;
maxIdex--;
}
}
public static bool IsNumberPalindrome(int number)
{
int reminder, sum = 0;
int tempNumber;
tempNumber = number;
bool IsPalindrome = false;
while (number > 0)
{
reminder = number % 10;
number = number / 10;
sum = sum * 10 + reminder;
if (tempNumber == sum)
{
IsPalindrome = true;
}
}
return IsPalindrome;
}

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

public static bool IsNumberPrime(int number)
{
int i;
for (i = 2; i <= number - 1; i++)
{
if (number % i == 0)
{
return false;
}
}
if (i == number)
{
return true;
}
return false;
}

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