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Vigenere Cipher, one of the assignments in Problem Set 2. It's like Caesar Cipher, but with a twist.
1
vote
Accepted
Can someone show me how to use isalpha() in an if() condition?
Isalpha takes as an argument a character, it is easy to use a for loop to iterate over each character in a string:
string name = "my name"; // char* name
for( int k = 0, s = strlen (name); k < …
1
vote
CS50 Week 2 Vigenere Problems
return ((c-97) & 26)
I think you don't want to use the operator '&', but the modulus operator '%', the first one is a bit-level operator. They affect the operands bit by bit, so the logical operatio …
3
votes
Accepted
pset2 vigenere arguments
The correct way isif(argc !=2 || ! isalpha(key[j]))
1
vote
Accepted
Pset2 Vigenere integer to pointer conversation
string Final = (((UI[i] - 'A') + tolower(key[a % keyl]) - 'a') % 26) + 'A';
It is an incorrect assignment:
(((UI[i] - 'A') + tolower(key[a % keyl]) - 'a') % 26) + 'A';
The above line is an integ …
0
votes
On running as ./a.out <keyword>
isalpha(argv[1])
Is the responsible declaration of segfault, argv[1] is a pointer to a string, isalpha() has as its argument a character.
If you do k = argv [1]; you can access each individual chara …
0
votes
Accepted
Segmentation Fault Vigenere
The problem is in the string keyletter, I suppose that it is destined to store the uppercase version of key, however you do:
string keyletter = 0;
This is to make the pointer keyletter point to NUL …
0
votes
Still being stuck in Vigenere
In vigenere change the letter with each letter of the text in clear, when we reach the final character of the keyword we start again with the first character, this suggests the use of the module with the … /vigenere <key>.\n");
return 1;
}
We have isolated a block of code that does a task, and it ends there when the check is done, we do not worry about it anymore. …
0
votes
pset2 vigenere; isalpha is accepting numbers in argv[1]
"The values returned are nonzero if the character c falls into the tested class, and a zero value if not." We can use that to build the if condition, the correct way would be:
if (! isalpha (key [a]) …
0
votes
PSET 2 problem!
else
{
printf ("%c", p[i]);
}
FOR loop will not consider whitespace, but if printed, anyway your formula is not correct, note that the formula for Vigenere is exactly the same as for Caesar, but …
0
votes
Accepted
cs50/pset2/vigenere why can't my code handle a key world of Hax0r2? code works otherwise
isalnum() checks for an alphanumeric character, argv[1] is not a character but a string (exactly a pointer to string),the right way would iterate over the length of argv [i] to check each character in …
1
vote
Accepted
segmentation fault error vigenere. help please
isalpha() do not accept a pointer but only characters, hence segfault. You must write isalpha(k[i]),the simplest thing is to use a for loop to iterate over each character, besides there are other erro …
1
vote
Accepted
Vigenere:non-alphabetical character
i<= strlen(keyword)
keep in mind that keyword begins with the zero subscript so that if its length is given by strlen the one index is strlen(keyword) - 1, the correct statement would be:
i < strle …
1
vote
Accepted
check50 pset2 vigenere problem
A really strange problem, everything is the fault of the following statement:
int j;
We have not initialized the variable j, after using gdb j it is set to zero inside the following statement:
j = …
1
vote
Accepted
My cipher algo is wiping out my keyword!
First of all, saying that trying to change a variable of type char * is not a good idea, however we can do this in vigenere because the function get_string () is using the dynamic allocation of memory …
1
vote
Accepted
pset2 Vigenere null pointer passed as argument 1, which is declared to never be null
Five functions for Vigenere seem excessive to me. Well, everything is a matter of preferences. …