brainfuck.c

#include <stdio.h>
unsigned char data[30000], *ptr = data;

void interpret(char* input) {
  char current;
  int i, loop;
  for (i = 0; input[i]; i++) {
    switch (input[i]) {
      case '>': ++ptr; break;
      case '<': --ptr; break;
      case '+': ++*ptr; break;
      case '-': --*ptr; break;
      case '.': putchar(data[ptr]); break;
      case ',': data[ptr] = getchar(); break;
      case '[': continue;
      case ']':
        for (loop = 1, current = input[--i]; loop;;) {
          if (current == '[') loop--;
          else if (current == ']') loop++;
        }
    }
  }
}

int main(int argc, char **argv) {
  int i;
  for (i = 0; i < 30000; i++) data[i] = 0;
  if (argc == 2) interpret(argv[1]);
  return 0;
}