diff options
Diffstat (limited to 'wk2/pset2')
| -rw-r--r-- | wk2/pset2/caesar/caesar.c | 37 |
1 files changed, 25 insertions, 12 deletions
diff --git a/wk2/pset2/caesar/caesar.c b/wk2/pset2/caesar/caesar.c index 75b52df..f4a52d3 100644 --- a/wk2/pset2/caesar/caesar.c +++ b/wk2/pset2/caesar/caesar.c @@ -8,15 +8,28 @@ int main(int argc, string argv[]) printf("%i\n", key); } -/*Implement your program in a file called caesar.c in a directory called caesar. -Your program must accept a single command-line argument, a non-negative integer. Let’s call it -for the sake of discussion. -If your program is executed without any command-line arguments or with more than one command-line argument, your program should print an error message of your choice (with printf) and return from main a value of 1 (which tends to signify an error) immediately. -If any of the characters of the command-line argument is not a decimal digit, your program should print the message Usage: ./caesar key and return from main a value of 1. -Do not assume that -will be less than or equal to 26. Your program should work for all non-negative integral values of less than . In other words, you don’t need to worry if your program eventually breaks if the user chooses a value for that’s too big or almost too big to fit in an int. (Recall that an int can overflow.) But, even if is greater than , alphabetical characters in your program’s input should remain alphabetical characters in your program’s output. For instance, if is , A should not become \ even though \ is positions away from A in ASCII, per asciitable.com; A should become B, since B is -positions away from A, provided you wrap around from Z to A. -Your program must output plaintext: (with two spaces but without a newline) and then prompt the user for a string of plaintext (using get_string). -Your program must output ciphertext: (with one space but without a newline) followed by the plaintext’s corresponding ciphertext, with each alphabetical character in the plaintext “rotated” by k positions; non-alphabetical characters should be outputted unchanged. -Your program must preserve case: capitalized letters, though rotated, must remain capitalized letters; lowercase letters, though rotated, must remain lowercase letters. -After outputting ciphertext, you should print a newline. Your program should then exit by returning 0 from main.*/ +/* +Your program must accept a single command-line argument, a non-negative integer. Let’s call it *k* + for the sake of discussion. +If your program is executed without any command-line arguments or with more than one command-line + argument, your program should print an error message of your choice (with printf) and return from + main a value of 1 (which tends to signify an error) immediately. +If any of the characters of the command-line argument is not a decimal digit, your program should print + the message Usage: ./caesar key and return from main a value of 1. +Do not assume that k will be less than or equal to 26. Your program should work for all non-negative + integral values of k less than 2^31-26. In other words, you don’t need to worry if your program eventually + breaks if the user chooses a value for k that’s too big or almost too big to fit in an int. (Recall + that an int can overflow.) But, even if k is greater than 26, alphabetical characters in your program’s + input should remain alphabetical characters in your program’s output. For instance, if k is 27, A should + not become \ even though \ is positions away from A in ASCII, per asciitable.com; A should become B, + since B is 27 positions away from A, provided you wrap around from Z to A. +Your program must output plaintext: (with two spaces but without a newline) and then prompt the user for + a string of plaintext (using get_string). +Your program must output ciphertext: (with one space but without a newline) followed by the plaintext’s + corresponding ciphertext, with each alphabetical character in the plaintext “rotated” by k positions; + non-alphabetical characters should be outputted unchanged. +Your program must preserve case: capitalized letters, though rotated, must remain capitalized letters; + lowercase letters, though rotated, must remain lowercase letters. +After outputting ciphertext, you should print a newline. Your program should then exit by returning 0 + from main. +*/ |