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So, I've figured out how to change the file headers and all. Works beautifully. The large image is the right size. I couldn't be happier. However, the large bmp image is just filled with neon green pixels. I would imagine that the part of my function that reads each pixel from the input file (pointer) and then writes it get stuck somewhere in a loop. I suppose it is not an infinite loop per se, since that would me I would spill over the allotted space for the bmp. I am really stuck here. My code follows below. Any and all hints would be greatly appreciated.

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Your problem is with your fseek()s.

You should fseek() back to beginning of the current line each time you read all the pixels of this line. You should do this n times for each line.

You should fseek() at the beginning of the next line after the n-th time you print a line.

Also, when you want to fseek() backwards, the offset parameter should be negative. In your case, your comment says that you fseek() backwards, but the offset is positive.

I hope this will help without spoiling the good part of figuring it out on your own. :D

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  • Thank you for your quick response. I've fixed what you suggested. It worked perfectly and the large.bmp output is indeed a multiple of the input file by factor n. I was so happy to see that. However, upon passing the function to check50 it presents me with these messages. I think that's strange considering the program does what it should. Is there a way to figure out what these messages mean, since there are kind of slashed into pieces? – Dominikus Dermann Jul 14 '17 at 15:45
  • ~/workspace/resize/ $ check50 2016.resize.less bmp.h resize.c :) resize.c and bmp.h exist :) resize.c compiles :( doesn't resize 1x1-pixel BMP when n is 1 \ expected an exit code of 0, not output of "Padding in: 3\nNew width: 3\nPadding: 3..." – Dominikus Dermann Jul 14 '17 at 15:46
  • :( resizes 1x1-pixel BMP to 2x2 correctly when n is 2 \ expected an exit code of 0, not output of "Padding in: 3\nNew width: 6\nPadding: 2..." :( resizes 1x1-pixel BMP to 3x3 correctly when n is 3 \ expected an exit code of 0, not output of "Padding in: 3\nNew width: 9\nPadding: 1..." :( resizes 1x1-pixel BMP to 4x4 correctly when n is 4 \ expected an exit code of 0, not output of "Padding in: 3\nNew width: 12\nPadding: ..." – Dominikus Dermann Jul 14 '17 at 15:46
  • :( resizes 1x1-pixel BMP to 5x5 correctly when n is 5 \ expected an exit code of 0, not output of "Padding in: 3\nNew width: 15\nPadding: ..." :( resizes 2x2-pixel BMP to 4x4 correctly when n is 2 \ expected an exit code of 0, not output of "Padding in: 2\nNew w – Dominikus Dermann Jul 14 '17 at 15:46
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    Nevermind, forgot to remove the fprints I put in place for debugging. Thank you so much for your help. I have removed the code form the original post for academic honesty! :) – Dominikus Dermann Jul 14 '17 at 15:48

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