interpret.c

void interpret(char *ptr, char *file_contents)
{
    int counter = 0;
    int target = counter - 1;

    while (*file_contents != '\0')
    {
        switch (*file_contents)
        {
        case INCREMENT_PTR:
            ++ptr;
            break;
        case DECREMENT_PTR:
            --ptr;
            break;
        case INCREMENT_VALUE:
            ++*ptr;
            break;
        case DECREMENT_VALUE:
            --*ptr;
            break;
        case PUT_VALUE:
            putchar(*ptr);
            break;
        case GET_VALUE:
            *ptr = getchar();
            break;
        case START_LOOP:
            ++counter;
            if (*ptr == 0)
                while (counter > 0)
                {
                    ++file_contents;
                    if (*file_contents == START_LOOP)
                        ++counter;
                    else if (*file_contents == END_LOOP)
                        --counter;
                }
            break;
        case END_LOOP:
            while (counter != target)
            {
                --file_contents;
                if (*file_contents == END_LOOP)
                    ++counter; // entered an inner loop
                else if (*file_contents == START_LOOP)
                    --counter; // exited a loop
            }
            --file_contents;
            break;
        default:
            printf("Unrecognized character: %c\n", *file_contents);
            break;
        }
        file_contents++;
    }

    printf(file_contents);
    printf("\n%d\n", counter);
}