Caesar's Cipher - C

[okkee]

Delete this before posting. Please make sure to include the language that you're using in the title, and use the <> button for any code.

Going through the cs50x course. Just asking for general tips. Thinking I did alright, but it's definitely a lot harder than python.

#include <cs50.h>
#include <stdio.h>
#include <string.h>

string caesar(string p, string q, int key);
bool all_digits(string s);
int keyint(string o, int initial);

int main(int argc, string argv[])
{
    if (argc != 2 || all_digits(argv[1]) != true)
    {
        printf("Usage: ./caesar key\n");
        return 1;
    }

    int sum = 0;

    int keynum = keyint(argv[1], sum);

    string original = get_string("plaintext:  ");

    char coded[strlen(original)];

    string changed = caesar(original, coded, keynum);

    printf("ciphertext: %s\n", changed);
}

bool all_digits(string s)
{
    for (int i = 0, n = strlen(s); i < n; i++)
    {
        if (s[i] < '0' || s[i] > '9')
        {
            return false;
        }
    }
    return true;
}

string caesar(string p, string q, int key)
{
    for (int i = 0, n = strlen(p); i < n; i++)
    {
        if (p[i] >= 'A' && p[i] <= 'Z')
        {
            q[i] = (char) (((p[i] - 'A') + key) % 26) + 'A';
        }
        else if (p[i] >= 'a' && p[i] <= 'z')
        {
            q[i] = (char) (((p[i] - 'a') + key) % 26) + 'a';
        }
        else
        {
            q[i] = p[i];
        }
    }
    q[strlen(p)] = '\0';
    return q;
}

int keyint(string o, int initial)
{
    for (int i = 0; o[i] != '\0'; i++)
    {
        initial = initial * 10 + (o[i] - 48);
    }
    return initial;
}

 

[mazylol]

Why did you declare the functions above main? Very weird to do it that way. Also not a huge fan of the Allman brace style, personally.

[okkee]

11 hours ago, mazylol said:

Why did you declare the functions above main? Very weird to do it that way. Also not a huge fan of the Allman brace style, personally.

 

On 9/26/2024 at 9:44 PM, okkee said:

string caesar(string p, string q, int key);
bool all_digits(string s);
int keyint(string o, int initial)

I'm guessing you mean this part here. I just kinda thought you had to put the prototype above main. Like, so that main doesn't think it's going to call a function that doesn't exist.

[mazylol]

6 hours ago, okkee said:

 

I'm guessing you mean this part here. I just kinda thought you had to put the prototype above main. Like, so that main doesn't think it's going to call a function that doesn't exist.

Typically you would just put main at the bottom of the program so you do not have to declare the functions like that. There is absolutely nothing wrong with doing it that way though.