Caesar test case suggestion

[lnevesabrantes]

I wrote a version of the Caesar code without the ctype library (no isdigit). It iterates over the characters in the argument and checks if they are digits using this condition:

if (argv[1][i] <= '0' || argv[1][i] >= '9')

This is wrong: it rejects 0 and 9 too. But check50 doesn't complain. Suggestion: write test cases using 0 or 9 as key.

[ivanharvard]

Thanks for submitting this issue!

I'm assuming that this a condition that checks:

if the ASCII value of the ith character in the key is smaller than the ASCII value of 0 or greater than the ASCII value of 9:
    return 1;

In theory, this should work. If it's an improper ASCII value for this character, then it must not be a digit. However, you probably realized by now that you've added an equality sign in your conditionals, so that the ASCII value of 0 and the ASCII value of 9 are also considered "non-digits" in your code.

While we try to make check50 as comprehensive as possible, there is always a chance certain code submissions fall through the cracks. For instance, check50 doesn't have a check for when the key is 13. So, a student may write in their code:

if (key == 13) {
    return 1;
}

And, while this would pass check50 and technically still be wrong, we would likely not add it into our check50 checks. It would be difficult to add every possible edge case to check50, and we avoid adding more test cases to check50 unless the error is encountered frequently or is pedagogically significant. However, we do appreciate the effort in putting in an issue and we will be sure to add such a test case if we notice that this issue is affecting more students than we realize! Thanks so much again!