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>> [MUSIC PLAYING]

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>> ROB BOWDEN: Hi.

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I'm Rob, and let's find
out who done it.

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So, starting with the template that
copy.c already gives us, we see that

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most of the code is going
to be the same.

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We are going to check to make sure
there's an infile and outfile

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specified at the command line, we're
going to open the infile for reading,

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we're going to open the outfile for
writing, and finally, we're going to

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read in the infile's headers, check to
make sure it's a valid bitmap, write

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the headers to the outfile, just as
copy.c has done, and we're going to

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iterate over the infile
scan lines in pixels.

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>> And now we see the only
change in this file.

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So, we read in a triple from the infile
as copy.c does, but instead of

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immediately writing the triple to the
outfile, we're going to change the

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pixel data.

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So we're going to set the blue data to
just 0, we're going to set the green

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to 0, leaving us with only the red, and
then we're going to write that to

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the outfile.

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And then the padding is going to be
exactly the same as it was in copy.c.

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Finally, close the files, return 0.

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>> So, let's see what happens.

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Let's make whodunit, ./whodunit,
clue.bmp, and lets reveal that bitmap.

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Let's look at the file.

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And we see Milo Banana dun it.

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My name is Rob, and this was whodunit.

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>> [MUSIC PLAYING]