Hexdump read offset with c lseek()

Question

I got an image file img.jpg and did the following
strings img.jpg | hexdump -C
which gave me this output
Now I need to get the camera and date information using ac programm with open, lseek and read ... My question is, how do I jump to the date 2015:08:05 with lseek?
I tried to use the offset 0x40 but don't really know what's going on ...

Edit: As pointed out in the answers the 2 of 2015 should be in 2015 but this code doesn't output 2 but 0.

int rd = lseek(filedesc, 0x49, SEEK_SET);


    if(rd < 0){
        perror("lseek");
        close(filedesc);
        return 1;
    }   

    read(filedesc, &output, 1);

    printf("%d", output);

Answer 1

0x40 is the address represents the beginning of the row. The 2 in 2015 is in address 0x49 - that's the address you need. Its content is 32 in Hexa or 2 as text.

In every row, the addresses go like that - for the line begins with 0x40 :

0x40 0x41 0x42 ... 0x48 0x49 0x4A 0x4B ... 0x4F . Then begins the next row.

The columns in the file are:

• Left column - the first address in the line.
• Middle column - the content of every address in Hexa.
• Right column - the content of every address in textual representation.

You should check of course that this offset is true for every JPG file.

ADDITION: Running hexdump -C will give different results when executing on strings img.jpg and when executing on img.jpg . If you're searching for a specific data in the file you should examine cat img.jpg | hexdump -C cat img.jpg | hexdump -C . The offsets there will fit the results of fopen the file and then lseek in it.