Using the CS50 library, this is my code but it keeps giving me a segmentation fault. I have tried to figure out where it keeps doing a segmentation fault, and for some reason it has to do with my function. Why does it keep doing this?
#import <cs50.h>
#import <stdio.h>
#import <ctype.h>
#import <string.h>
string ciphertext(string plaintext[1], string key[1]);
int main(int argc, string argv[])
{
// Variables
string plaintext2[1];
if (argc == 2)
{
if(strlen(argv[1]) == 26)
{
string text = get_string("plaintext: ");
plaintext2[0] = text;
}
else
{
printf("Key must contain 26 characters.\n");
return 1;
}
}
else
{
printf("Usage: ./substitution key\n");
return 1;
}
string ciphertext2 = ciphertext(&plaintext2[0], &argv[1]);
printf("ciphertext: %s\n", ciphertext2);
}
string ciphertext(string plaintext[1], string key[1])
{
// Variables
string ciphertext[1];
for (int i = 0; i < strlen(plaintext[0]); i++)
{
if (plaintext[0][i] == 'a')
{
ciphertext[0][i] = tolower(key[0][0]);
}
else if (plaintext[0][i] == 'A')
{
ciphertext[0][i] = toupper(key[0][0]);
}
else if (plaintext[0][i] == 'b')
{
ciphertext[0][i] = tolower(key[0][1]);
}
else if (plaintext[0][i] == 'B')
{
ciphertext[0][i] = toupper(key[0][1]);
}
else if (plaintext[0][i] == 'c')
{
ciphertext[0][i] = tolower(key[0][2]);
}
else if (plaintext[0][i] == 'C')
{
ciphertext[0][i] = toupper(key[0][2]);
}
else if (plaintext[0][i] == 'd')
{
ciphertext[0][i] = tolower(key[0][3]);
}
else if (plaintext[0][i] == 'D')
{
ciphertext[0][i] = toupper(key[0][3]);
}
else if (plaintext[0][i] == 'e')
{
ciphertext[0][i] = tolower(key[0][4]);
}
else if (plaintext[0][i] == 'E')
{
ciphertext[0][i] = toupper(key[0][4]);
}
else if (plaintext[0][i] == 'f')
{
ciphertext[0][i] = tolower(key[0][5]);
}
else if (plaintext[0][i] == 'F')
{
ciphertext[0][i] = toupper(key[0][5]);
}
else if (plaintext[0][i] == 'g')
{
ciphertext[0][i] = tolower(key[0][6]);
}
else if (plaintext[0][i] == 'G')
{
ciphertext[0][i] = toupper(key[0][6]);
}
else if (plaintext[0][i] == 'h')
{
ciphertext[0][i] = tolower(key[0][7]);
}
else if (plaintext[0][i] == 'H')
{
ciphertext[0][i] = toupper(key[0][7]);
}
else if (plaintext[0][i] == 'i')
{
ciphertext[0][i] = tolower(key[0][8]);
}
else if (plaintext[0][i] == 'I')
{
ciphertext[0][i] = toupper(key[0][8]);
}
else if (plaintext[0][i] == 'j')
{
ciphertext[0][i] = tolower(key[0][9]);
}
else if (plaintext[0][i] == 'J')
{
ciphertext[0][i] = toupper(key[0][9]);
}
else if (plaintext[0][i] == 'k')
{
ciphertext[0][i] = tolower(key[0][10]);
}
else if (plaintext[0][i] == 'K')
{
ciphertext[0][i] = toupper(key[0][10]);
}
else if (plaintext[0][i] == 'l')
{
ciphertext[0][i] = tolower(key[0][11]);
}
else if (plaintext[0][i] == 'L')
{
ciphertext[0][i] = toupper(key[0][11]);
}
else if (plaintext[0][i] == 'm')
{
ciphertext[0][i] = tolower(key[0][12]);
}
else if (plaintext[0][i] == 'M')
{
ciphertext[0][i] = toupper(key[0][12]);
}
else if (plaintext[0][i] == 'n')
{
ciphertext[0][i] = tolower(key[0][13]);
}
else if (plaintext[0][i] == 'N')
{
ciphertext[0][i] = toupper(key[0][13]);
}
else if (plaintext[0][i] == 'o')
{
ciphertext[0][i] = tolower(key[0][14]);
}
else if (plaintext[0][i] == 'O')
{
ciphertext[0][i] = toupper(key[0][14]);
}
else if (plaintext[0][i] == 'p')
{
ciphertext[0][i] = tolower(key[0][15]);
}
else if (plaintext[0][i] == 'P')
{
ciphertext[0][i] = toupper(key[0][15]);
}
else if (plaintext[0][i] == 'q')
{
ciphertext[0][i] = tolower(key[0][16]);
}
else if (plaintext[0][i] == 'Q')
{
ciphertext[0][i] = toupper(key[0][16]);
}
else if (plaintext[0][i] == 'r')
{
ciphertext[0][i] = tolower(key[0][17]);
}
else if (plaintext[0][i] == 'R')
{
ciphertext[0][i] = toupper(key[0][17]);
}
else if (plaintext[0][i] == 's')
{
ciphertext[0][i] = tolower(key[0][18]);
}
else if (plaintext[0][i] == 'S')
{
ciphertext[0][i] = toupper(key[0][18]);
}
else if (plaintext[0][i] == 't')
{
ciphertext[0][i] = tolower(key[0][19]);
}
else if (plaintext[0][i] == 'T')
{
ciphertext[0][i] = toupper(key[0][19]);
}
else if (plaintext[0][i] == 'u')
{
ciphertext[0][i] = tolower(key[0][20]);
}
else if (plaintext[0][i] == 'U')
{
ciphertext[0][i] = toupper(key[0][20]);
}
else if (plaintext[0][i] == 'v')
{
ciphertext[0][i] = tolower(key[0][21]);
}
else if (plaintext[0][i] == 'V')
{
ciphertext[0][i] = toupper(key[0][21]);
}
else if (plaintext[0][i] == 'w')
{
ciphertext[0][i] = tolower(key[0][22]);
}
else if (plaintext[0][i] == 'W')
{
ciphertext[0][i] = toupper(key[0][22]);
}
else if (plaintext[0][i] == 'x')
{
ciphertext[0][i] = tolower(key[0][23]);
}
else if (plaintext[0][i] == 'X')
{
ciphertext[0][i] = toupper(key[0][23]);
}
else if (plaintext[0][i] == 'y')
{
ciphertext[0][i] = tolower(key[0][24]);
}
else if (plaintext[0][i] == 'Y')
{
ciphertext[0][i] = toupper(key[0][24]);
}
else if (plaintext[0][i] == 'z')
{
ciphertext[0][i] = tolower(key[0][25]);
}
else if (plaintext[0][i] == 'Z')
{
ciphertext[0][i] = toupper(key[0][25]);
}
else
{
ciphertext[0][i] = plaintext[0][i];
}
}
return ciphertext[0];
}
I really need some help, and I don't know why it keeps giving a fault.
The array
is uninitialized and has indeterminate value.
Accessing such an array the way like this
results in undefined behavior.
You need to allocate a character array with the size equal to the value of the expression
Pay attention to that instead the numerous if-else statement you could define a string literal like for example
and then you can use the standard string function
strchr
like