Brainfuck Interpreter

gistfile1.c

#include <stdio.h>
 
static unsigned char cell[30000];
static unsigned char *ptr;
 
void processCommand(char command, FILE *file)
{  
    char cmd;
    long pos;
 
    switch (command)
    {
        case '+':
        {
            ++*ptr;
            break;
        }
 
        case '-':
        {
            --*ptr;
            break;
        }
 
        case '>':
        {
            ++ptr;         
            break;
        }
 
        case '<':
        {
            --ptr;         
            break;
        }
 
        case '.':
        {
            putchar(*ptr);
            break;
        }
 
        case ',':
        {
            *ptr = getchar();
            break;
        }
 
        case '[':
        {
            pos = ftell(file);
            while(*ptr)
            {
                fseek(file, pos, SEEK_SET);
                cmd = getc(file);
 
                while (cmd != ']' && cmd != EOF)
                {
                    processCommand(cmd, file);
                    cmd = getc(file);
                }
            }
        }
    }
}
 
int main(int argc, char *argv[], char **envp[])
{          
    ptr = &cell[0];
    if (argc < 2)
    {
        return 0;
    }
    else
    {              
        FILE *bf = fopen(argv[1], "r");
 
        char cmd;
        while ((cmd = getc(bf)) != EOF)
        {
            processCommand(cmd, bf);
        }          
 
        fclose(bf);
    }      
   
    return 0;
}