Segmentation fault in substitution ciphertext - c

Question

I am implementing a substitution ciphertext scheme. It's an assignment
from the CS50 course.
The input are the substitution scheme and the plaintext and the
program should write back the ciphertext.
$ ./encrypt QWERTYUIOPASDFGHJKLZXCVBNM HE
IT
I keep getting segmentation fault and I am not sure why. This is the source of my solution.
#include <cs50.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
int result (string words);
int main (int argc, string argv[])
{
if (argc == 2)
{
if (strlen (argv[1]) == 26)
{
int k = 0;
for (int i = 0; i<strlen(argv[1]); i++)
{
if (((int)argv[1][i] > 64 && (int)argv[1][i] < 91) || ((int)argv[1][i] > 96 && (int)argv[1][i] < 123))
{
k +=1;
}
}
if (k==26)
{
char new_var[strlen(argv[1])];
for (int j = 0, n = strlen(argv[1]); j < n; j++)
{
new_var[j] = toupper((char)argv[1][j]) ;
}
string key = new_var;
printf ("%i", result(key));
if (result (key) == 3)
{
string word = get_string("plaintext: ") ;
char mutated_word [strlen(word)];
for (int i = 0; word[i] != '\0'; i++)
{
if ((int)word[i]>64 && (int)word[i]<91)
{
mutated_word[i] = key[(int)word[i] - 65] ;
}
else if ((int)word[i]>96 && (int)word[i]<123)
{
mutated_word[i] = (char) ((int)(key[(int)word[i]-97]) + 32) ;
}
else
{
mutated_word[i] = word[i] ;
}
}
printf("ciphertext: %s\n", mutated_word);
return 0;
}
else
{
printf ("Usage: ./substitution keya\n");
return 1;
}
}
else
{
printf ("Usage: ./substitution keyb\n");
return 1;
}
}
else
{
printf ("Usage: ./substitution keyc\n");
return 1;
}
}
else
{
printf ("Usage: ./substitution keyd\n");
return 1;
}
}
int result (string words)
{
int conclusion = 3;
for (int j = 0; j< strlen(words) - 1 ; j++)
{
for(int i =j+1; i<strlen(words) - 1; j++)
{
if ((int)words[i] == (int)words[j])
{
conclusion = 4;
}
}
}
return conclusion;
}

Answer 1

Check your 'Result' function
In it, check your 2nd for loop...
int result (string words)
{
int conclusion = 3;
for (int j = 0; j< strlen(words) - 1 ; j++)
{
for(int i =j+1; i<strlen(words) - 1; j++)
{
if ((int)words[i] == (int)words[j])
{
conclusion = 4;
}
}
}
return conclusion;
}
Don't think you have replaced 'i' with 'j'. j++
No Segmentation fault
Then it will not show segmentation fault, pls check your code thoroughly always.