string message = "Find what is (inside the parentheses)";

int openingPosition = message.IndexOf('(');
int closingPosition = message.IndexOf(')');

Console.WriteLine(openingPosition); // 13
Console.WriteLine(closingPosition); // 36

string message = "What is the value <span>between the tags</span>?";

const string openSpan = "<span>";
const string closeSpan = "</span>";

int openingPosition = message.IndexOf(openSpan);
int closingPosition = message.IndexOf(closeSpan);

openingPosition += openSpan.Length;
int length = closingPosition - openingPosition;
Console.WriteLine(message.Substring(openingPosition, length)); // between the tags

string message = "hello there!";

int first_h = message.IndexOf('h');
int last_h = message.LastIndexOf('h');
Console.WriteLine($"For the message: '{message}', the first 'h' is at position {first_h} and the last 'h' is at position {last_h}."); 
// For the message: 'hello there!', the first 'h' is at position 0 and the last 'h' is at position 7.

string message = "Hello, world!";
char[] charsToFind = { 'a', 'e', 'i' };

int index = message.IndexOfAny(charsToFind);

Console.WriteLine($"Found '{message[index]}' in '{message}' at index: {index}."); // Found 'e' in 'Hello, world!' at index: 1.

string data = "12345John Smith          5000  3  ";
string updatedData = data.Remove(5, 20);
Console.WriteLine(updatedData); // 123455000  3  

string message = "This--is--ex-amp-le--da-ta";
message = message.Replace("--", " ");
message = message.Replace("-", "");
Console.WriteLine(message); // This is example data

string greeting = "      Hello World!       ";
Console.WriteLine($"[{greeting}]"); // "      Hello World!       "

string trimmedGreeting = greeting.TrimStart();
Console.WriteLine($"[{trimmedGreeting}]"); // "Hello World!       "

trimmedGreeting = greeting.TrimEnd();
Console.WriteLine($"[{trimmedGreeting}]"); // "      Hello World!"

trimmedGreeting = greeting.Trim();
Console.WriteLine($"[{trimmedGreeting}]"); // "Hello World!"

string songLyrics = "You say goodbye, and I say hello";
Console.WriteLine(songLyrics.Contains("goodbye")); // True
Console.WriteLine(songLyrics.Contains("greetings")); // False