C# language note

Date: July 29, 2024 Tags: C# language

Summary

This document provides a list of common C# methods and features spanning various categories like string manipulation, list operations, and more.

String Methods:

• s.Split(separator): Split string into array.
• s.Trim(): Remove leading and trailing whitespace.
• s.StartsWith(prefix): Check if starts with prefix.
• s.EndsWith(suffix): Check if ends with suffix.
• s.IndexOf(sub): Find substring.
• s.Replace(old, new): Replace substring.
• s.ToUpper(): Convert to uppercase.
• s.ToLower(): Convert to lowercase.
• s.Substring(startIndex, length): Retrieve substring starting from the specified index with the specified length.
• s.Contains(substring): Check if string contains substring.

StringBuilder Methods:

• sb.Append(str): Append string to the builder.
• sb.Insert(index, str): Insert string at the specified index.
• sb.Replace(oldStr, newStr): Replace all occurrences of a specified string.
• sb.Remove(startIndex, length): Remove characters from the specified start index and length.
• sb.Clear(): Clear all characters from the builder.
• sb.ToString(): Convert the builder to a string.
• sb.Length: Get or set the length of the builder.
• sb[index]: Get or set the character at the specified index.

List Methods:

• list.Add(item): Add item to list.
• list.AddRange(collection): Append all items in the specified collection to the list.
• list.Remove(item): Remove the first occurrence of the specified item.
• list.RemoveAt(index): Remove the item at the specified index.
• list.IndexOf(item): Return the index of the first occurrence of the specified item.
• list.LastIndexOf(item): Return the index of the last occurrence of the specified item.
• list.Clear(): Remove all items from the list.
• list.Contains(item): Check if the list contains the specified item.
• list.Count: Get the number of items in the list.
• list.Insert(index, item): Insert the item at the specified index.
• list.Sort(): Sort the items in the list.

Queue Methods:

• queue.Enqueue(item): Add item to the end of the queue.
• queue.Dequeue(): Remove and return the item at the beginning of the queue.
• queue.Peek(): Return the item at the beginning of the queue without removing it.
• queue.Contains(item): Check if the queue contains the specified item.
• queue.Clear(): Remove all items from the queue.
• queue.Count: Get the number of items in the queue.

Dictionary Methods:

• dict.Add(key, value): Add the specified key and value to the dictionary.
• dict.Remove(key): Remove the value with the specified key.
• dict.ContainsKey(key): Check if the dictionary contains the specified key.
• dict.TryGetValue(key, out value): Get the value associated with the specified key.
• dict.Clear(): Remove all keys and values from the dictionary.
• dict.Keys: Get a collection containing the keys in the dictionary.
• dict.Values: Get a collection containing the values in the dictionary.

Examples of Using List:

1. Creating and Using a List: ```csharp List list = new List(); list.Add("apple"); list.Add("banana"); list.Add("cherry");

foreach (string item in list) { Console.WriteLine(item); }

2. **Inserting an Item at a Specific Index**:
```csharp
List<int> numbers = new List<int> { 1, 2, 3, 4, 5 };
numbers.Insert(2, 10);

foreach (int number in numbers)
{
    Console.WriteLine(number);
}
// Output: 1, 2, 10, 3, 4, 5

1. Removing an Item from a List: ```csharp List fruits = new List { "apple", "banana", "cherry" }; fruits.Remove("banana");

foreach (string fruit in fruits) { Console.WriteLine(fruit); } // Output: apple, cherry

4. **Checking if a List Contains an Item**:
```csharp
List<string> fruits = new List<string> { "apple", "banana", "cherry" };
bool hasApple = fruits.Contains("apple");
Console.WriteLine(hasApple); // Output: True

1. Sorting a List: ```csharp List numbers = new List { 5, 1, 4, 3, 2 }; numbers.Sort();

foreach (int number in numbers) { Console.WriteLine(number); } // Output: 1, 2, 3, 4, 5

6. **Finding the Index of an Item in a List**:
```csharp
List<string> fruits = new List<string> { "apple", "banana", "cherry" };
int index = fruits.IndexOf("cherry");
Console.WriteLine(index); // Output: 2

1. Clearing a List: ```csharp List fruits = new List { "apple", "banana", "cherry" }; fruits.Clear(); Console.WriteLine(fruits.Count); // Output: 0

8. **Adding a Range of Items to a List**:
```csharp
List<int> numbers = new List<int> { 1, 2, 3 };
List<int> moreNumbers = new List<int> { 4, 5, 6 };
numbers.AddRange(moreNumbers);

foreach (int number in numbers)
{
    Console.WriteLine(number);
}
// Output: 1, 2, 3, 4, 5, 6