Brainfuck.txt

import java.util.*;

class BrainFuck
{
	private static Scanner ob = new Scanner(System.in);
	private static int ptr; // Data pointer
	
	// Max memory limit. It is the highest number which
	// can be represented by an unsigned 16-bit binary
	// number. Many computer programming environments
	// beside brainfuck may have predefined
	// constant values representing 65535.
	private static int length = 65535;
	
	// Array of byte type simulating memory of max
	// 65535 bits from 0 to 65534.
	private static byte memory[] = new byte[length];
	
	// Interpreter function which accepts the code
	// a string parameter
	private static void interpret(String s)
	{
		int c = 0;
		
		// Parsing through each character of the code
		for (int i = 0; i < s.length(); i++)
		{
			// BrainFuck is a tiny language with only
			// eight instructions. In this loop we check
			// and execute all those eight instructions
			
			
			// > moves the pointer to the right
			if (s.charAt(i) == '>')
			{
				if (ptr == length - 1)//If memory is full
					ptr = 0;//pointer is returned to zero
				else
					ptr ++;
			}
			
			// < moves the pointer to the left
			else if (s.charAt(i) == '<')
			{
				if (ptr == 0) // If the pointer reaches zero

					// pointer is returned to rightmost memory
					// position
					ptr = length - 1;
				else
					ptr --;
			}
			
			// + increments the value of the memory
			// cell under the pointer
			else if (s.charAt(i) == '+')
				memory[ptr] ++;

			// - decrements the value of the memory cell
			// under the pointer
			else if (s.charAt(i) == '-')
				memory[ptr] --;

			// . outputs the character signified by the
			// cell at the pointer
			else if (s.charAt(i) == '.')
				System.out.print((char)(memory[ptr]));

			// , inputs a character and store it in the
			// cell at the pointer
			else if (s.charAt(i) == ',')
				memory[ptr] = (byte)(ob.next().charAt(0));

			// [ jumps past the matching ] if the cell
			// under the pointer is 0
			else if (s.charAt(i) == '[')
			{
				if (memory[ptr] == 0)
				{
					i++;
					while (c > 0 || s.charAt(i) != ']')
					{
						if (s.charAt(i) == '[')
							c++;
						else if (s.charAt(i) == ']')
							c--;
						i ++;
					}
				}
			}

			// ] jumps back to the matching [ if the
			// cell under the pointer is nonzero
			else if (s.charAt(i) == ']')
			{
				if (memory[ptr] != 0)
				{
					i --;
					while (c > 0 || s.charAt(i) != '[')
					{
						if (s.charAt(i) == ']')
							c ++;
						else if (s.charAt(i) == '[')
							c --;
						i --;
					}
					i --;
				}
			}
		}
	}

	// Driver code
	public static void main(String args[])
	{
		System.out.println("Enter the code:");
		String code = ob.nextLine();
		System.out.println("Output:");
		interpret(code);
	}
}