Caesar

Caesar.c

/*
 Description: Takes in a input and outputs a "secret" output for easy
  encryption.
 
*/
#include <stdlib.h>
#include <stdio.h>
#include <cs50.h>
#include <string.h>
#include <ctype.h>
 
/*
 Displays a encrypted character using the original character and key
*/
void Display(char orginalCharacter, int key);
 
/*
 Main program run
*/
int main(int argc, char* argv[])
{
    if (argc != 2)
    {
        printf("usage ceaser {NUM} \n");
        return 1;
    }
 
    int offset = atoi(argv[1]);
    string message = GetString();
    
    
    for (int counter=0; counter != strlen(message); counter++)
    {
        if (isalpha(message[counter]))
        {
            Display(message[counter], offset);
             
        } 
            else 
        {
            printf("%c", message[counter]);
        }
     }  
     
    printf("\n");
}
 
 
void Display(char orginalCharacter, int decoderKey)
{
    string alphabet = "abcdefghijklmnopqrstuvwxyz";
    int key = ( (tolower (orginalCharacter) - 'a') + decoderKey) % 26;
    char result = alphabet[key];
 
    if (isupper(orginalCharacter))
    {
        result = toupper(result);
    }
 
    printf("%c", result);
}