cs50 pset2/caesar

caesar

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

int main(int argc, string argv[])
{
    //int number = atoi(argv[1]); // convert the string argv to use it in the if condition
    // checking if the user use the command line comands correctly or not
    if ((argc != 2) || (atoi(argv[1]) < 0))
    {
        printf ("Usage: ./caesar k\n");
        return 1;
    }
    int x = 0;
    string plaintext = get_string("plain text: ");
    int charactars = strlen(plaintext); // getting the number for the charactars to use it later in the for loop
    //string ciphertext = plaintext;
    printf("ciphertext: ");
    for(int i = 0; i < charactars; i++) //loop over each charactar the user has enter to check if it's a letter or not and cipher it or leave it if it's not a letter
        {
            char letter = plaintext[i];
            if (isalpha(letter))
            {

                x = letter;
                x += atoi(argv[1]); // convert the string the user has provied as a key and use it in the cipher

                if (isalpha(x))
                {
                    printf("%c", x);
                }
                else
                {
                    do // this loop just in case the user enter huge number I actually used goto; but I heard it's not that good so I wrote the loop
                    {
                        x -=26;
                    }
                    while (!isalpha(x));
                        printf("%c", x);
                }
            }
            else
            {
                printf("%c",plaintext[i]);
            }

        }
        printf("\n");
    return 0;
}