Basic brainfuck interpreter in C.

brainfuck.c

#include <stdio.h>

#define T_LEN 30000

int main (void)
{
    unsigned char tape[T_LEN] = {0};
    unsigned char *pointer = tape;

    char inp_tape[T_LEN];
    fgets (inp_tape, T_LEN, stdin);

    int pos = 0;
    int active_l, keep;

    while (inp_tape[pos] != '\0') {
        switch (inp_tape[pos]) {
            case '+':   (*pointer)++;   if (*pointer > 255)         return 1;
                        break;
            case '-':   (*pointer)--;   if (*pointer < 0)           return 1;
                        break;
            case '>':   pointer++;      if (pointer - tape > T_LEN) return 1;
                        break;
            case '<':   pointer--;      if (pointer - tape < 0)     return 1;
                        break;
            case '.':   putchar (*pointer);
                        break;
            case ',':   *pointer = getchar ();
                        break;
            case '[':
                if (!*pointer) {
                    keep = 1;

                    while (keep > 0) {
                        pos++;
                        if (inp_tape[pos] == '[')
                            keep++;
                        else if (inp_tape[pos] == ']')
                            keep--;
                    }
                }
                else break;
            case ']':
                if (*pointer) {
                    active_l = 1;

                    while (active_l > 0) {
                        pos--;
                        if (inp_tape[pos] == '[')
                            active_l--;
                        else if (inp_tape[pos] == ']')
                            active_l++;
                    }
                }
                break;
        }
        pos++;
    }

    return 0;
}