brainf__k.cs

using System;
using System.Collections.Generic;

namespace Brainf__k
{
    class Program
    {
        static void Main(string[] args)
        {
            int length = 1024;
            if (args.Length > 0){
                try
                {
                    length = int.Parse(args[0]);
                    if (length < 1024) length = 1024;
                }
                catch (FormatException) { }
            }

            int pos = 0;
            char[] memory = new char[length];

            Console.WriteLine("------------------------------");
            Console.WriteLine("    Brainf**k  interpreter    ");
            Console.WriteLine("------------------------------");

            while (true)
            {
                try
                {
                    Console.WriteLine();
                    Console.Write("> ");
                    string buffer = Console.ReadLine();

                    if (buffer.Length == 0) break;

                    Stack<int> stack = new Stack<int>();

                    for (int i = 0; i < buffer.Length; i++)
                    {
                        char c = buffer[i];
                        switch (c)
                        {
                            case '>': pos++; break;
                            case '<': pos--; break;
                            case '+': memory[pos]++; break;
                            case '-': memory[pos]--; break;
                            case '.': Console.Write(memory[pos]); break;
                            case ',': memory[pos] = Console.ReadKey(true).KeyChar; break;
                            case '[':
                                if (memory[pos] == 0)
                                {
                                    for (int nest = 1; i < buffer.Length || nest == 0; i++)
                                    {
                                        if (buffer[i] == '[') nest++;
                                        else if (buffer[i] == ']') nest--;
                                    }
                                }
                                else stack.Push(i);
                                break;
                            case ']':
                                if (memory[pos] != 0) i = stack.Pop() - 1;
                                break;
                            case 'c':
                                memory = new char[length];
                                pos = 0;
                                break;
                        }
                    }
                }
                catch (Exception e)
                {
                    Console.WriteLine("Error: " + e.Message);
                }
            }
        }
    }
}