bf.c

#include <unistd.h>

int main(int ac, char **av) {
	char brank, *ptr, *input, optab[4096] = {0};

	if (ac <= 1) {
		write(1, "\n", 1);
		return 0;
	}
	ptr = optab;
	input = av[1];
	while (*input) switch (*input) {
		case '>': ++ptr;
			goto next;
		case '<': --ptr;
			goto next;
		case '+': ++*ptr;
			goto next;
		case '-': --*ptr;
			goto next;
		case '.': write(1, ptr, 1);
			goto next;
		case '[':
			goto next;
		case ']': brank = 1;
			if (*ptr) do switch (*--input) {
				case '[':
					--brank;
					break;
				case ']':
					++brank;
				default:
					break;
			} while (brank > 0);
			goto next;
		next:
		default:
			++input;
			break;
	}
	return 0;
}