Caesar solution

Caesar.c

@@ -0,0 +1,106 @@
+#include <cs50.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <string.h>
+bool isDigit(string arg)
+{
+    /*
+     * This function for checking if the argv[1] is all made of numbers.
+     * accepts string "arg" to check if it is all numbers.
+     * returns boolean argument to continue the work flow of the cipher.
+     */
+    bool isDIGIT = true;
+    int length = strlen(arg);
+    for (int i = 0; i < length; i++)
+    {
+        /*
+         * Going to iterate for all charecters or "Numbers" in this string
+         * to check if it's numbers or not .. if it was not a number the
+         * boolean value will change to false .
+         */
+        if (!(isdigit(arg[i])))
+        {
+            isDIGIT = false;
+        }
+    }
+    return isDIGIT;
+}
+//encryption function 
+void encipher(string plainText, int key)
+{
+    /*
+     * This function will encipher the given string from the user.
+     * Will seprate the alphapatical letters to two sections:
+     *     - Capital letters and will be encripted aside.
+     *     - Small letters and will be encripted aside.
+     * Then all of the letters will be printed to the user side by side.
+     * will accept int key for shifting the letters, string plainText which will be encrypted.
+     * will not return anything so it is void
+     */
+    char capital[26] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'};
+    char small[26] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};
+    //Taking the length of the given string to help with the "for" loop.
+    int length = strlen(plainText);
+    //Making an array of charecters to hold the encrypted charecters.
+    char ciphertext[length];
+    //a variable to help with finding the right element of the letters' arrays to use it.
+    int numnum = 0;
+
+    for (int i = 0; i < length; i++)
+    {
+        if (isupper(plainText[i]))
+        {
+            int letter = plainText[i] - 'A';
+            numnum = (letter + key) % 26;
+            ciphertext[i] = capital[numnum];
+        }
+        else if (islower(plainText[i]))
+        {
+            int letter = plainText[i] - 'a';
+            numnum = (letter + key) % 26;
+            ciphertext[i] = small[numnum];
+        }
+        else
+        {
+            // This section for the "none-alphapatical charecters" like "," or numbers
+            ciphertext[i] = plainText[i];
+        }
+    }
+    //printing the result for the user.
+    printf("ciphertext: ");
+    for (int i = 0 ; i < length; i++)
+    {
+        printf("%c", ciphertext[i]);
+    }
+    printf("\n");
+}
+int main(int argc, string argv[])
+{
+    if (argc == 2)
+    {
+        //if the user managed successfuly to put 2 argument vectors then we need to check
+        //the "argv[1]" if it was written all by numbers.
+        bool isDIGIT = isDigit(argv[1]);
+        if (!(isDIGIT))
+        {
+            printf("Usage: ./caesar key\n");
+            return 1;
+        }
+        else
+        {
+            //coverting the key from "string" to "int".
+            int key = atoi(argv[1]);
+            //taking input from the user for the text that they want to encipher
+            string plainText = get_string("plaintext:  ");
+            //encrypting the text and printing it.
+            encipher(plainText, key);
+
+        }
+    }
+    else
+    {
+        printf("Usage: ./caesar key\n");
+        return 1;
+    }
+}