brainfuck.py

import sys

def execute(code):
        code = ''.join([x for x in code if x in '.,+-<>[]'])
        cells,ptr,i = [0]*3000,0,0
        while i < len(code):
                c = code[i]
                if c == '>': ptr += 1
                if c == '<': ptr -= 1
                if c == '+': cells[ptr] += 1
                if c == '-': cells[ptr] -= 1
                if c == '.': sys.stdout.write(chr(cells[ptr]))
                if c == ',': cells[ptr] = ord(sys.stdin.read(1))
                if c == '[' and cells[ptr] == 0: i = code.find("]",i)
                if c == ']': i = code[:i].find('[')-1
                i += 1

if __name__ == '__main__':
        hello_world = "++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>."
        execute(hello_world)

bug on lines 14 and 15. think about nested loops.