Hello o/ I have been trying to get my forth interpreter working but I can't even parse it properly without error. here is what I have done so for ( it's my 3rd attempt ). if you know any good resources to learn compiler design then please link it. Thank you in advance! ```c# namespace test; public enum TokenType { Number, Operator, String, Identifier, FunctionStart, FunctionEnd, } public class Token { public TokenType Type { get; set; } public string Value { get; set; } public override string ToString() { return $"{Type}: {Value}"; } } public class Program { public static void Err() { Console.WriteLine("error"); } public static void Main(string[] args) { string code = "12 12 : abc 10 . ; 23 - + "; List tokens = new List(); bool stringMode = false; int startStringIndex = 0; for (int cur = 0; cur < code.Length; cur++) { char ch = code[cur]; if (stringMode) { if (ch == '"' && code[cur-1] != '\\') { stringMode = false; string strValue = code.Substring(startStringIndex, cur - startStringIndex); tokens.Add(new Token { Type = TokenType.String, Value = strValue }); } } switch (ch) { case '+': case '-': case '*': case '/': { tokens.Add(new Token { Type = TokenType.Operator, Value = ch.ToString() }); break; } case '.': { if (cur + 1 < code.Length && code[cur+1] == '"') { stringMode = true; cur+=2; // Skip the opening quote startStringIndex = cur; } else { tokens.Add(new Token { Type = TokenType.Operator, Value = ch.ToString() }); } break; } case >= '0' and <= '9': { int start = cur; while (cur + 1 < code.Length && code[cur + 1] >= '0' && code[cur + 1] <= '9') { cur++; } string numberValue = code.Substring(start, cur - start + 1); tokens.Add(new Token { Type = TokenType.Number, Value = numberValue }); break; } case (>= 'a' and <= 'z') or (>= 'A' and <= 'Z'): { int start = cur; while (cur + 1 < code.Length && ((code[cur + 1] >= 'a' && code[cur + 1] <= 'z') || (code[cur + 1] >= 'A' && code[cur + 1] <= 'Z') || (code[cur + 1] >= '0' && code[cur + 1] <= '9') || code[cur + 1] == '_')) { cur++; } string identifierValue = code.Substring(start, cur - start + 1); tokens.Add(new Token { Type = TokenType.Identifier, Value = identifierValue }); break; } case ':': { tokens.Add(new Token { Type = TokenType.FunctionStart, Value = ch.ToString() }); break; } case ';': { tokens.Add(new Token { Type = TokenType.FunctionEnd, Value = ch.ToString() }); break; } case ' ': case '\n': { break; } default: { Err(); Console.WriteLine("Something went wrong!"); break; } } } foreach (var token in tokens) { Console.WriteLine(token); } } } ```

☭可爱小猫☭