How to get the width/height of jpeg file without using library?

Question

Firstly I want to say I tried many times to find the answer by using google search, and I found many results but I did not understand, because I don\'t know the idea of read

Answer 1

then you have to find hight and width marker of jpeg that is [ffc0].

after finding ffc0 in binary formate, the the four,five bytes are hight and six and seven bytes are width.

eg: [ff c0] d8 c3 c2 [ff da] [00 ff]
                      |         |
                      |         |
                      ->height  ->width

int position;
unsigned char len_con[2];
/*Extract start of frame marker(FFC0) of width and hight and get the position*/
for(i=0;i<FILE_SIZE;i++)
{
    if((image_buffer[i]==FF) && (image_buffer[i+1]==c0) )
    {
        position=i;
    }
}
/*Moving to the particular byte position and assign byte value to pointer variable*/
position=position+5;
*height=buffer_src[position]<<8|buffer_src[position+1];
*width=buffer_src[position+2]<<8|buffer_src[position+3];

printf("height %d",*height);
printf("width %d",*width);