CS50 - pset2 - Substitution - "output not valid ASCII text" - c

Question

My program is producing what is seems like the correct output but i still get the :( message when i run check50. I have already read other awnsers to similar questions but none of them seems actually similar to my problem.
check50 output:
:) substitution.c exists
:) substitution.c compiles
:) encrypts "A" as "Z" using ZYXWVUTSRQPONMLKJIHGFEDCBA as key
:) encrypts "a" as "z" using ZYXWVUTSRQPONMLKJIHGFEDCBA as key
:) encrypts "ABC" as "NJQ" using NJQSUYBRXMOPFTHZVAWCGILKED as key
:) encrypts "XyZ" as "KeD" using NJQSUYBRXMOPFTHZVAWCGILKED as key
:) encrypts "This is CS50" as "Cbah ah KH50" using YUKFRNLBAVMWZTEOGXHCIPJSQD as key
->:( encrypts "This is CS50" as "Cbah ah KH50" using yukfrnlbavmwzteogxhcipjsqd as key
output not valid ASCII text
->:( encrypts "This is CS50" as "Cbah ah KH50" using YUKFRNLBAVMWZteogxhcipjsqd as key
output not valid ASCII text
:) encrypts all alphabetic characters using DWUSXNPQKEGCZFJBTLYROHIAVM as key
:) does not encrypt non-alphabetical characters using DWUSXNPQKEGCZFJBTLYROHIAVM as key
:) handles lack of key
:) handles too many arguments
:) handles invalid key length
:) handles invalid characters in key
:) handles duplicate characters in key
:) handles multiple duplicate characters in key
I put the -> before the error messages for easier visualization
It is weird because right before the two errors there is an almost identical input/output that has been checked as correct
Here is my code:
#include <cs50.h>
#include <stdio.h>
#include <ctype.h>
#include <string.h>
string subs(string plain, string key);
int key_check(string key);
int main(int argc, string argv[]) {
// CHECK IF IT HAS AN INPUT
if (argc < 2) {
printf("Usage: ./substitution key\n");
return 1;
}
// CHECK IF IT HAS MORE THAN 1 INPUT
if (argc > 2) {
printf("Usage: ./substitution key\n");
return 1;
}
// IF KEYCHECK FUNCTION DETECTS AN ERROR, RETURN 1
if (key_check(argv[1]) == 1) {
return 1;
}
// ELSE KEY = USER ARGV INPUT
string key = argv[1];
// GET USER PLAINTEXT INPUT
string plain = get_string("plaintext: ");
string cipher = subs(plain, key);
// PRINT RESULT
printf("ciphertext: %s\n", cipher);
}
int key_check(string key) {
// STRING LENGHT
int leng = strlen(key);
// CHECK IF KEY HAVE 26 CHARACTERS
if (leng < 26) {
printf("Key must contain 26 characters.\n");
return 1;
}
for (int i = 0; i < leng; i++) {
// CHECK IF KEY ONLY HAVE ALPHABET CHARACTERS
if (isalpha(key[i]) == 0) {
printf("Key must contain only alphabet characters\n");
return 1;
}
// CHECK IF KEY HAVE REPEATED CHARACTER
for (int i2 = 0; i2 < 26; i2++) {
if (i != i2) {
if (key[i] == key[i2]) {
printf("Key must have each character exactly one time\n");
return 1;
}
}
}
}
return 0;
}
string subs(string plain, string key) {
// GET PLAINTEXT LENGHT
int leng = strlen(plain);
// CREATES CIPHER STRING
string cipher = plain;
// CREATES AN ARRAY FOR UPPER KEY
int UPPER[26];
for (int i2 = 0; i2 < 26; i2++) {
if (isupper(key[i2]) > 0 ) {
UPPER[i2] = key[i2];
}
else {
UPPER[i2] = key[i2] - 32;
}
}
// CREATES AN ARRAY FOR LOWER KEY
int LOWER[26];
for (int i3 = 0; i3 < 26; i3++) {
if (islower(key[i3] > 0)) {
LOWER[i3] = key[i3];
}
else {
LOWER[i3] = key[i3] + 32;
}
}
for (int i = 0; i < leng; i++) {
if (isupper(plain[i]) > 0) {
cipher[i] = UPPER[plain[i] - 65];
}
else if (islower(plain[i]) > 0) {
cipher[i] = LOWER[plain[i] - 97];
}
else {
cipher[i] = plain[i];
}
}
return cipher;
}
It all leads me to think that it is a check50 problem, but with my lack of experience with coding and problem solving it can be anything.
Thanks in advance.

Answer 1

The line if (islower(key[i3] > 0)) { has parentheses in the wrong place. It should be:
if( islower(key[i3]) > 0 ){
or (more typical in C):
if( islower(key[i3]) ){

Answer 2

To get upper and lower working.
Lowercase needs to point to i2.
for (int i2 = 0; i2 < 26; i2++) {
if (islower(key[i2] > 0)) {
LOWER[i2] = key[i2];
}
else {
LOWER[i2] = key[i2] + 32;