c program problem

algorithm..

opens a file containing hex values (jpeg image)

obtains the first four bytes and compares with 0xe0ffd8ff or 0xe1ffd8ff to check whether it is the start of a jpeg image.

if so, copies 512 bytes into the first file..(jpeg's are stored in 512 byte block)

repeats the process...


problem...

goes into an infinite loop at the second while condition




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


typedef uint32_t DWORD;


typedef struct
{
DWORD initial;


} CHECK;




int main(void)
{
FILE* fp1;


char title[8];




CHECK jp;
int count = 1;


if ((fp1 = fopen("card.raw", "r")) == NULL)
{
printf("file1 open error");
return 1;
}
fread(&jp, sizeof(CHECK), 1, fp1);


while ((jp.initial != 0xe0ffd8ff && jp.initial != 0xe1ffd8ff))
{
fseek(fp1, 508, SEEK_CUR);
fread(&jp, sizeof(CHECK), 1, fp1);


}
fseek(fp1, -4, SEEK_CUR);


do
{
FILE* fp2;
sprintf(title, "%3d.jpg", count);


if ((fp2 = fopen(title, "w")) == NULL)
{
printf("file open error");
}




fgets(buf, sizeof(buf), fp2);
fread(&jp, sizeof(CHECK), 1, fp1);




while ((jp.initial != 0xe0ffd8ff && jp.initial != 0xe1ffd8ff))
{
fseek(fp1, -4, SEEK_CUR);
fwrite(fp1, 512, 1, fp2);


}
fclose(fp2);
count++;
}
while (!feof(fp1));
return 0;
}

cyber said:

fgets(buf, sizeof(buf), fp2);
fread(&jp, sizeof(CHECK), 1, fp1);




while ((jp.initial != 0xe0ffd8ff && jp.initial != 0xe1ffd8ff))
{

Click to expand...

ignore fgets it is commented