Coding Toolkit for C#

Array

int[] nums = new int[n];
int[] nums = { 4, 3, 1, 2 };

nums.Length // Length of the array
for(int i = 0; i < nums.Length; i++) { nums[i] } // Iterate
Array.Sort(nums) // 1 2 3 4
Array.Reverse(nums) // 4 3 2 1

int[,] numbers = { {1, 4, 2}, {3, 6, 8} };
numbers[0, 1] // Accessing element output: 4
numbers.GetLength(0) 
numbers.GetLength(1)

String

string str = "Hello Developers"
char[] arr = str.ToCharArray();
string str = new string(arr);

// Iterate and get length is same as array

if(str.IsNullOrEmpty(str)) 
if(str.IsNullOrWhiteSpace(str))
if(str.Equals("Hello")) // false

int firstIndex = str.IndexOf('e'); // 1
int lastIndex = str.LastIndexOf('e') // 13

str.Substring(startIndex); 
str.Substring(startIndex, length) 
str.Trim() // Trim leading and trailing whitespaces

str.ToLower() // "hello developers"
str.ToUpper() // "HELLO DEVELOPERS"
str.Replace('e', 'a') // "Hallo Davalopars"

int number = 42;
string str = "42"
Convert integer -> string:   num.ToString() // "42"
Parse  string -> integer :   int.tryParse(str, out int result) // boolean

String Builder

StringBuilder stringBuilder = new StringBuilder();
stringBuilder.Append("Hello");
stringBuilder.Insert(2, "She"); // "HeShello"
stringBuilder.Replace("She", "") // "Hello"
string newString = stringBuilder.ToString();

List

// Create a list
List<int> integerList = new List<int>();
List<int> integerList = new List<int> { 10, 20, 30, 40, 50 };
List<int> integerList = integerArray.ToList(); // array -> list

// Iterate the list
foreach (int number in integerList) {
}

integerList.Add(42);
integerList.Add(10);

// Check whether an element exists in the list
if(integerList.Contains(30)) {
    integerList.Remove(30);
}

// Get an element at particular index
int element = integerList[index]; 

// Convert list into array
int[] integerArray = integerList.ToArray();

Stack

System.Collections.Generic

Stack<int> stack = new Stack<int>();

stack.Push(1);
stack.Push(2);
stack.Push(3);

Console.WriteLine("Top item:" + stack.Peek());

while(stack.Count > 0) {
    int poppedItem = stack.Pop();
    Console.WriteLine("Popped: " + poppedItem);    
}

Queue

Queue<int> queue = new Queue<int>;
queue.Enqueue(1);
queue.Enqueue(2);
queue.Enquque(3);

Console.WriteLine("Front item:" + stack.Peek());

int dequeuedItem = queue.Dequeue(); // 1

bool contains = queue.Contains(1) // true
int[] queueArray = queue.ToArray();

while(queue.Count > 0) {
    int dequeuedItem = queue.Dequeue();
    Console.WriteLine("Dequeued: " + dequeuedItem);
}

// Removes all items from queue
queue.Clear();

Dictionary

// Create a map
Dictionary<string, int> map = new Dictionary<string, int>();

// Add entries in the map
map.Add("one", 1);
map.Add("two", 2);

// Check if key exists in the map
if(map.ContainsKey("two")) { 
    Console.WriteLine("Value for key: " + map["tw0"]);
    map["two"] = -1; // Replace value
}

int value;
if (map.TryGetValue("two", out value)){
    Console.WriteLine("Value for key: " + value);
}

// Access both keys and values
foreach(var pair in map) { 
    Console.WriteLine($"Key: {pair.Key}, Value: {pair.Value}");
}

// Access keys
foreach(string key in map) {
    Console.WriteLine(key);
}

map.Remove("one"); // Remove entry from the map

Math

Namespace: System.Math

Int32.MaxValue - Maximum value of an int data type.

Math.Abs - Absolute value of a number

Math.Round - Rounds a floating point number to the nearest integer

Math.Pow - Number raised to the specified power

Math.Min(num1, num2) - Minimum of two number