Thread: how read an image file?

i'm trying reading a JPG\GIF file, it's a binary file true and i must see it's structure for it... now i have these link about JPG format image:
JPEG File Layout and Format

like we know the file is combined with 1 or 2 or 4 bytes on types.
for now, i just need read the size. so heres the information:
"SOF0 (Start Of Frame 0) marker:

Field Size Description

Marker Identifier 2 bytes 0xff, 0xc0 to identify SOF0 marker

Length 2 bytes This value equals to 8 + components*3 value

Data precision 1 byte This is in bits/sample, usually 8
(12 and 16 not supported by most software).

Image height 2 bytes This must be > 0

Image Width 2 bytes This must be > 0"

i must find the "SOF0" mark... but how can i search?
the file data is on these variable:

Code:

BMPSize bmp;    FILE* img = fopen(filename, "rb");   //read the file
    char header[256];
    fread(header, sizeof(unsigned char), 256, img); // read the 54-byte header

now heres how i test if is "SOF0":

Code:

size_t i =0;

        do
        {
            if( strcmp(header, "SOF0")==0)
            {
                printf("hello");
                width = *(int*)&header[i+2];
                height= *(int*)&header[i+4];
                break;
            }
            i++;
        }while(i<strlen(header));

so what i'm doing wrong for compare?

maybe you have right, but i'm trying understand why i'm wrong.. i'm trying learning
i'm trying adapt that code to my code

why allways you get that conclusion?????
true i don't know, that's i'm asking, but tell me how i compare correctly is for make my work?????

that's true... i'm trying understand more 2 functions then i can share some code and information..