String

Declaring and initializing strings

// Declare without initializing.
string message1;

// Initialize to null.
string? message2 = null;

// Initialize as an empty string.
// Use the Empty constant instead of the literal "".
string message3 = System.String.Empty;

// Initialize with a regular string literal.
string oldPath = "c:\\Program Files\\Microsoft Visual Studio 8.0";

// Initialize with a verbatim string literal.
string newPath = @"c:\Program Files\Microsoft Visual Studio 9.0";

// Use System.String if you prefer.
System.String greeting = "Hello World!";

// In local variables (i.e. within a method body) you can use implicit typing.
var temp = "I'm still a strongly-typed System.String!";

// Use a const string to prevent 'message4' from being used to store another string value.
const string message4 = "You can't get rid of me!";

// Use the String constructor only when creating a string from a char*, char[], or sbyte*. See System.String documentation for details.
char[] letters = { 'A', 'B', 'C' };
string alphabet = new string(letters);

NOTE:

To prevent NullReferenceException errors, initialize strings using the string.Empty constant (or "") instead of null. This creates a valid string object with zero length. Before accessing a string, use the string.IsNullOrEmpty() method to safely check its state.

Key Takeaways:

• Avoid null: Use string.Empty to ensure the object exists.
• Literal Form: The value is represented as "".
• Safety First: Use string.IsNullOrEmpty(yourString) as a defensive coding practice to verify values before use.

Immutability of strings

string s1 = "A string is more ";
string s2 = "than the sum of its chars.";

// Concatenate s1 and s2. This actually creates a new string object and stores it in s1, releasing the reference to the original object.
s1 += s2;

System.Console.WriteLine(s1);
// Output: A string is more than the sum of its chars.

string str1 = "Hello "; 
string str2 = str1; // refrence of string 
str1 += "World"; // modified string create new ref for str1;

System.Console.WriteLine(str2);
//Output: Hello

Quoted string literals

string columns = "Column 1\tColumn 2\tColumn 3";
//Output: Column 1        Column 2        Column 3

string rows = "Row 1\r\nRow 2\r\nRow 3";
/* Output:
    Row 1
    Row 2
    Row 3
*/

string title = "\"The \u00C6olean Harp\", by Samuel Taylor Coleridge";
//Output: "The Æolean Harp", by Samuel Taylor Coleridge


string filePath = @"C:\Users\scoleridge\Documents\";
//Output: C:\Users\scoleridge\Documents\

string text = @"My pensive SARA ! thy soft cheek reclined
    Thus on mine arm, most soothing sweet it is
    To sit beside our Cot,...";
/* Output:
My pensive SARA ! thy soft cheek reclined
    Thus on mine arm, most soothing sweet it is
    To sit beside our Cot,...
*/

string quote = @"Her name was ""Sara.""";
//Output: Her name was "Sara."