replacing all string characters with new characters

Question

Hello everyone,
would anyone have an idea of how to loop through a string and replace the characters of that string with a new set of characters? For instance, if I wanted to change the characters in, string letters_1 = "abcdef", with the characters in, string letters_2 = "zxcvbn" to have "letters_1" print "zxcvbn" instead of "abcdef".
I've tried multiple different ways, but can't seem to get how to loop through both strings and change "abcdef" to "qufhte. below, I need to loop through "plaintext" and change those characters with argv[1] characters.
Also just as a note, I'm using the cs50 library. That's why I can use "string" and "get_string" Any help is appropriate.
Thank you!
https://code.sololearn.com/c6a20A14a6A2

Answer 1

Does this clear it up?
I don't know what is in your cs50.h library so I didn't rely on get_string or string. It looks like string is basically "char *" but you'll have to test that.
I wasn't sure if you needed to process both upper and lower case so I did both.
You could probably copy and use this encrypt function in your code.
/*
Assumes replacement_alphabet is at least as long as the alphabet(26). replacement_alphabet should be limited to lower case letters.
Assumes the result has enough allocated memory to store the full length of input.
*/
void encrypt(const char * input, const char *replacement_alphabet, char * result)
{
int i;
char c;
// loop through all characters of input.
for (i = 0; input[i] != '\0'; i++) {
c = input[i];
if (c >= 'a' && c <= 'z') // if lower case
result[i] = replacement_alphabet[c - 'a'];
else if (c >= 'A' && c <= 'Z') // if upper case letter
result[i] = replacement_alphabet[c - 'A'] + ('A' - 'a');
else
result[i] = c;
}
result[i] = '\0'; // mark end of null-terminated string.
}
int main()
{
const char *replacement_alphabet = "vchprzgjntlskfbdqwaxeuymoi";
const char * input = "Hello, World";
char result[256];
/*
plaintext: hello, world
ciphertext: jrssb, ybwsp
*/
encrypt(input, replacement_alphabet, result);
printf("%s", result);
}

Answer 2

Josh Greig just added to my code. It works great! Thank you so much!

Answer 3

David wrote, "Josh Greig just added to my code. It works great! Thank you so much!"
Response:
good stuff.