C# syntax, system library functions should be memorized

Try to use them if the interviewer allows to do so.

string

Property

• Length

Method

• ToCharArray()
• Remove(index, length)
• IndexOf(c)

Array

Initialization

• // Single-dimensional array (numbers).
  int[] n1 = new int[4] {2, 4, 6, 8};
  int[] n2 = new int[] {2, 4, 6, 8};
  int[] n3 = {2, 4, 6, 8};
  // Single-dimensional array (strings).
  string[] s1 = new string[3] {"John", "Paul", "Mary"};
  string[] s2 = new string[] {"John", "Paul", "Mary"};
  string[] s3 = {"John", "Paul", "Mary"};
  
  // Multidimensional array.
  int[,] n4 = new int[3, 2] { {1, 2}, {3, 4}, {5, 6} };
  int[,] n5 = new int[,] { {1, 2}, {3, 4}, {5, 6} };
  int[,] n6 = { {1, 2}, {3, 4}, {5, 6} };
  
  // Jagged array.
  int[][] n7 = new int[2][] { new int[] {2,4,6}, new int[] {1,3,5,7,9} };
  int[][] n8 = new int[][] { new int[] {2,4,6}, new int[] {1,3,5,7,9} };
  int[][] n9 = { new int[] {2,4,6}, new int[] {1,3,5,7,9} };

Method

• Array.Reverse(arr)
• Array.Sort(arr)

List

Method

• Add()
• AddRange()

HashTable / Dictionary

Property

• Count
• Keys
• Values

Method

• Contains(K)
• ContainsKey(K) (same as Contains)
• ContainsValue(V)

HastSet

Method

• ToArray()

Stack

Property

• Count

Method

• Push()
• Pop()
• Peek()

Queue

Property

• Count

Method

• Enqueue()
• Dequeue()
• Peek()

File Operation

Read file in steam mode

            using (FileStream contents = File.OpenRead(fileName))
            using (StreamReader reader = new StreamReader(contents))
            {
                while (!reader.EndOfStream)
                {
                    Console.WriteLine(reader.ReadLine());
                }
            }