Brainf*** Interpter

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

unsigned char tape[30000] = {0}; // Set the tape equal to zero, bf only calls for 30000 bytes available in the tape
unsigned char* ptr = tape; // The pointer to the tape, this is what we work with!

int main(int argc, char *argv[]){
    // The file handling section

    // Make sure there is an argument to the interpter
    if(argc < 2){
        printf("\nCorrect usage is: bfi <source.txt>\n");
        exit(8); // Exit program
    }
    // Read in the input from a text based file
    FILE *file;
    file = fopen(argv[1], "r"); // Read the file to file...
    int p, size;
    p = size = 0; // Set stuff equal to zero
    char c; // Current char beind read
    // Read stuff into the char array.
    if(file == NULL){
        printf("\nFile could not be opened!\n");
        exit(8); // Exit the program
    }
    // make char input array size of required input
    fseek(file, 0, SEEK_END);
    size = ftell(file);
    fseek(file, 0, SEEK_SET);
    char input[size]; // Set up the input for proper size
    while((c=fgetc(file)) != EOF)
        input[p++] = (char) c; // Read in the file
    fclose(file); // Close the file, we have the input array

    // The interpter section
    int i, loop; // Iterator and loop counter
    for(i = 0; input[i] != 0; i++){ // Go through 1 command at a time
        c = input[i]; // get current char
        // Interpet the commands according to wikipedia's article
        if(c == '+')
            ++*ptr;
        else if(c == '-')
            --*ptr;
        else if(c == '>')
            ++ptr;
        else if(c == '<')
            --ptr;
        else if(c == ',') // get input
            *ptr = getchar();
        else if(c == '.') // print current char
            putchar(*ptr);
        else if(c == '[') // skip over this, go to ] section
            continue;
        else if(c == ']' && *ptr){ // make sure there is something in *ptr
            loop = 1; // We are in a loop!
            while(0 < loop){ // While we are still in a loop
                c = input [--i]; // Get c
                if(c == '[')
                    loop--; // No more loop!
                else if(c == ']')
                    loop++; // Another loop!
            }
        }
    }
    return 0;
}