cs50 pset4 recover.c

recover.c

#include <cs50.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>

#define CHUNK 512

typedef uint8_t BYTE;

int main(void)
{
    // open "card.raw"  
    FILE* inptr = fopen("card.raw", "r");
    if (inptr == NULL)
    {
        return 1;
    }
    
    // set JPG counter
    int jpg = 0;
    
    // initialize file pointer
    FILE* outptr = NULL;
    
    // process the file
    while (!feof(inptr))
    {
        // create buffer
        BYTE buffer[CHUNK];
        
        // read data into buffer
        fread(&buffer, sizeof(buffer), 1, inptr);
        
        // are we at the start of a JPG?
        if (buffer[0] == 255 && buffer[1] == 216 && buffer[2] == 255 &&
            (buffer[3] == 224 || buffer[3] == 225))
        {
            // close an open outptr if one is open
            if (jpg >= 1)
            {
                fclose(outptr);
            }   
            
            // what file should we put data into
            char FILENAME[8];
            sprintf(FILENAME, "%03d.jpg", jpg);
            outptr = fopen(FILENAME, "w");
            jpg++;
        }
        
        if (jpg > 0)
        {           
            fwrite(&buffer, sizeof(buffer), 1, outptr);
        }
    }
    
    // close the output file
    fclose(outptr);
    
    // close the input file
    fclose(inptr);
}