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I'm almost finished with the ´vigenereproblem set incs50` but have one problem my brain can't find the solutions for, anyone have any ideas?

check50 2015.fall.pset2.vigenere vigenere.c:
:) vigenere.c exists
:) vigenere.c compiles
:) encrypts "a" as "a" using "a" as keyword

**:( encrypts "world, say hello!" as "xoqmd, rby gflkp!" using "baz" as keyword
\ expected output, but not "xoqmd, szz gflkp!\n"**
:) encrypts "BaRFoo" as "CaQGon" using "BaZ" as keyword
:) encrypts "BARFOO" as "CAQGON" using "BAZ" as keyword
:) handles lack of argv[1]
:) handles argc > 2
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It appears you are "consuming" a char in the key when you encounter a non-alpha character in the message, even though you (correctly) do not change the value of the char in the message. That explains why only "say" is encrypted incorrectly.

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  • Thanks for answering. I am aware of this but I don't understand why since there is isalpha function in the loop.
    – lkoks
    Commented Jun 16, 2016 at 15:16
  • Let's say you are using j to cycle through the key one character at a time. It looks like you are incrementing j when isalpha() is false. From the spec: if your code is about to apply the jth character of k to the ith character of p,but the latter proves to be a non-alphabetical character, you must wait to apply that jth character ofk to the next alphabetical character in p; you must not yet advance to the next character in k.
    – DinoCoderSaurus
    Commented Jun 16, 2016 at 16:51
  • Now it works! Thanks for help:)
    – lkoks
    Commented Jun 17, 2016 at 9:11

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