A simple brainfuck interpreter.

brainfuck.c

#include <stdio.h>
#include <stdlib.h>

#define MEM_SIZE 3000

void interpret(char* instruction) {
    unsigned char* tape = (unsigned char*)malloc(MEM_SIZE * sizeof(char));

    unsigned char* ptr = &tape[0];
    for (;*instruction; ++instruction) {
        switch(*instruction) {
            case '>':
                ptr++;
                break;
            case '<':
                ptr--;
                break;
            case '+':
                ++*ptr;
                break;
            case '-':
                --*ptr;
                break;
            case ',':
                *ptr = getchar();
                break;
            case '.':
                putchar(*ptr);
                break;
            case '[':
                if(!*ptr) {
                    size_t loop = 1;

                    while (loop) {
                        ++instruction;
                        if (*instruction == ']') --loop;
                        if (*instruction == '[') ++loop;
                    }
                }
                break;
            case ']':
                if (*ptr) {
                    size_t loop = 1;

                    while (loop) {
                        --instruction;
                        if (*instruction == '[') --loop;
                        if (*instruction == ']') ++loop;
                    }
                }
                break;
            default:
                printf("Invalid character '%c'\n", *ptr);
        }
    }

    free(tape);
}

int main(int args, char* arg[]){
    interpret("++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.");
    return 1;
}