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I face a problem in which the function isjpgheader() never ever returns true for any photo. I would appreciate if someone can offer some advice as to why the function is not working, thank you very much!

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Your code has at least two problems, probably more. First, your isjpgheader() has to check the first 4 bytes of header[]. Now look at how it's defined: BYTE header[3]; The 4th byte doesn't exist. Only 3 bytes, byte 0, byte 1, and byte 2 exist.

Next, you have an infinite loop in your first while loop. It depends on finding that first signature, but since it isn't finding it, it loops forever. It would be a good idea to also check for EOF to terminate an infinite read loop. The reason for the infinite loop is that you read the first 4 bytes, then you reset the pointer back 4 bytes. You're reading the same 4 bytes over and over!

That will get you going, but you might want to reconsider your design. The code is far more complicated than it needs to be! There are 6 fread calls, multiple variables to hold the same data, multiple fwrite and fseek calls, etc. Over time, I've noticed that the more fread calls, the more error-prone the code becomes. You should be thinking about efficient code.

There's an old programming adage, "KISS - Keep It Simple, Stupid!" I tell myself this on just about every project that I work on. Also, if it feels too complicated, it probably is. This program can be implemented with a single fread, a single fwrite, and no calls to fseek. All you need to do is read in a block, decide what to do based on the first 4 bytes and whether an output file is open, and then do it.

Just some things to think about.

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  • Thank you! Silly error on arrays there haha. I will rewatch Zamyla's walkthrough and try again.
    – Wet Feet
    Feb 10 '16 at 15:41

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