.NET API Reference

System Namespace

Provides fundamental classes and base types that define primitive data types, event access, exception classes, math functionalities, and more.

Types

• String
• Int32
• Double
• DateTime
• Console
• Exception

System.String

Represents text as a sequence of UTF-16 code units. This is a reference type.

Members

• Length : int

  Gets the number of characters in the current String object.

• IsNullOrEmpty(string value) : bool

  Indicates whether the specified string is null or an empty string ("").

• Contains(string value) : bool

  Determines whether the specified substring occurs within this string.

• ToUpper() : string

  Converts this string to uppercase.

Example

string message = "Hello, World!";
Console.WriteLine(message.Length); // Output: 13
Console.WriteLine(string.IsNullOrEmpty("")); // Output: True
Console.WriteLine(message.Contains("World")); // Output: True
Console.WriteLine(message.ToUpper()); // Output: HELLO, WORLD!

System.Console

Provides standard input, output, and error streams, along with other members that can be used to query information about the current environment or to manage the runtime.

Members

• WriteLine(string value) : void

  Writes the specified value to the standard output stream.

• ReadLine() : string

  Reads the next line of characters from the standard input stream and returns as a string.

Example

Console.WriteLine("Enter your name:");
string name = Console.ReadLine();
Console.WriteLine($"Hello, {name}!");