jharvard@appliance (~/Dropbox/pset2): check50 2014/x/pset2/caesar caesar.c
    :) caesar.c exists
    :) caesar.c compiles
    :( encrypts "a" as "b" using 1 as key
       \ expected output, not standard error of "/opt/sandbox50/bin/run.sh: line 31: 215..."
    :( encrypts "barfoo" as "yxocll" using 23 as key
       \ expected output, not standard error of "/opt/sandbox50/bin/run.sh: line 31: 215..."
    :( encrypts "BARFOO" as "EDUIRR" using 3 as key
       \ expected output, not standard error of "/opt/sandbox50/bin/run.sh: line 31: 215..."
    :( encrypts "BaRFoo" as "FeVJss" using 4 as key
       \ expected output, not standard error of "/opt/sandbox50/bin/run.sh: line 31: 215..."
    :( encrypts "barfoo" as "onesbb" using 65 as key
       \ expected output, not standard error of "/opt/sandbox50/bin/run.sh: line 31: 214..."
    :( encrypts "world, say hello!" as "iadxp, emk tqxxa!" using 12 as key
       \ expected output, not standard error of "/opt/sandbox50/bin/run.sh: line 31: 215..."
    :) handles lack of argv[1]
    https://sandbox.cs50.net/checks/2f449728b97446c58778fc95360f4897
    jharvard@appliance (~/Dropbox/pset2): ./caesar 1
    a
    b
    jharvard@appliance (~/Dropbox/pset2): ./caesar 3
    BARFOO
    EDUIRR
    jharvard@appliance (~/Dropbox/pset2):