My program for resize.c is able to resize the bmp's provided with the pset4, for example small.bmp, smiley.bmp but after running the command check50 2014.fall.pset4.resize bmp.h resize.c on terminal window it gives me the following error message: :) resize.c and bmp.h exist :) resize.c compiles :( doesn't resize 1x1-pixel BMP when n is 1 :( resizes 1x1-pixel BMP to 2x2 correctly when n is 2 :( resizes 1x1-pixel BMP to 3x3 correctly when n is 3 :( resizes 1x1-pixel BMP to 4x4 correctly when n is 4 :( resizes 1x1-pixel BMP to 5x5 correctly when n is 5 :( resizes 2x2-pixel BMP to 4x4 correctly when n is 2 https://sandbox.cs50.net/checks/2f70d3ffbac74984b510768f0245003f please tell me what does this error mean?

Thank you.

1 Answer 1


Basically, it's saying that your program isn't working. Other than compiling, everything has failed. Have you actually checked the images created? More importantly, have you looked at the header sections of each output file using the tools described in the instructions (peek) to make sure they are correct?

The two most common problems are incorrect header processing and errors calculating padding, often resulting in black pixels.

Having said that, there have been problems with check50 lately, but they're supposed to be fixed now. (Have you run update50?) Try running check50 several times. If you get successful results, it's probably check50. If the results are consistent failures, it's something with your program.

If this answers your question, please accept the answer to close the question. Let's keep up on forum housekeeping. ;-)

  • Is it necessary to match the headers with the staff implementation of the program Jun 16, 2015 at 22:25
  • Each entire output file, including the headers, must be perfect. Any errors and it fails. It's that simple. Now, that means that you need to understand the header structure and what needs to be updated in order to write the code to do so.
    – Cliff B
    Jun 16, 2015 at 22:27
  • okay, then may i ask you some questions about the headers Jun 16, 2015 at 22:30
  • yes. If it would be easier, I am over on slack in the psets room. If you're not there, ask away.
    – Cliff B
    Jun 16, 2015 at 22:32
  • what is bfSize, biHeight and biSizeImage? Jun 16, 2015 at 22:40

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