This is in C language. When I call rotate() in main, the function returns false for isalpha() even though the string entered for plaintext uses alphabetic characters. Perhaps it’s identifying an alphabetic character by its ASCII value (‘A’ = 65)? I tried to test that out and used (char) with the letter variable in rotate() but it didn’t change anything.
PORTION OF MAIN
string plaintext = get_string("plaintext: ");
int length = strlen(plaintext);
char ciphertext[length];
for (int i = 0; i < length; i++)
{
ciphertext[i] = rotate(plaintext[i], key);
}
ROTATE FUNCTION
char rotate(char letter, int key)
{
if (isalpha(letter) == true)
{ ...
Return value
Non-zero value if the character is an alphabetic character, zero otherwise.
You should be either checking for not equal to 0 instead of true, as its not necessarily guaranteed to be 1 ~= true, or removing the comparison entirely
Also make sure that your loop condition is < and not “& lt” without the space unless that’s a weird formatting issue
For more information, make sure to check the documentation for the standard library functions
Ah ha! Yes, I did check the docs but I think I just glanced over that portion. Be more careful next time. Now that I took another look at the other ctype.h functions, they all return 1 or 0. I think I confused equivalent python built-in functions as those evaluated to true/false.
The < is a less than sign but it seems it doesn’t render correctly on Lemmy.
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isalphadocumentation:You should be either checking for not equal to 0 instead of true, as its not necessarily guaranteed to be
1~=true, or removing the comparison entirelyAlso make sure that your loop condition is < and not “& lt” without the space unless that’s a weird formatting issue
For more information, make sure to check the documentation for the standard library functions
Ah ha! Yes, I did check the docs but I think I just glanced over that portion. Be more careful next time. Now that I took another look at the other ctype.h functions, they all return 1 or 0. I think I confused equivalent python built-in functions as those evaluated to true/false. The < is a less than sign but it seems it doesn’t render correctly on Lemmy.
I would drop the “== true” entirely. C will evaluate any nonzero int as true in an “if” statement.
Good point!
Never, ever write “== true” or “== false” unless it’s absolutely necessary. In C that’s pretty close to never.