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JoshuaMejia5.c
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JoshuaMejia5.c
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#include <stdio.h>
#include <stdlib.h>
void menu();
void menu() {
printf("Main Menu\n");
for (int i = 0; i < 30; i++)
{
printf("-");
}
printf("\nPlease Choose a Selection :) \n 1. Encrypt \n 2. Decrypt \n 3. Exit \n");
}
int encrypt(int str, int shiftKey) {
if(str >= 'a' && str <= 'z'){
return 'a' + ((str - 'a' + shiftKey) % 26);
}
else if(str >= 'A' && shiftKey <= 'Z'){
return 'A' + ((str - 'A' + shiftKey) % 26);
}
else{
return str;
}
}
int decrypt(int str, int shiftKey) {
if(str >= 'a' && str <= 'z'){
return 'a' + ((str - 'a' + (26-shiftKey)) % 26);
}
else if(str >= 'A' && shiftKey <= 'Z'){
return 'A' + ((str - 'A' + (26 - shiftKey)) % 26);
}
else{
return str;
}
}
int main(int argc, char *argv[]) {
int opt, ch, key;
//Loop until exit
while(1) {
menu(); //print menu
scanf("%d", &opt);
//functions time :D
switch(opt){
//Encrypt
case 1:
printf("\n**To Return to the Menu, press CTRL+D**");
printf("\nEnter the shift key: ");
scanf("%d", &key);
printf("Enter the string to encrypt: ");
if(argc == 2) { //run program with one command-line argument
key = atoi(argv[1]); //convert ASCII to integer for key entered
}
while((ch = getchar()) != EOF) { //find alternative eventually . . .
printf("%c", encrypt(ch, key));
}
printf("\n");
break;
//Decrypt
case 2:
printf("**To Return to the Menu, press CTRL+D**");
printf("\nEnter the shift key: ");
scanf("%d", &key);
printf("Enter the string to decrypt: ");
if(argc == 2) {
key = atoi(argv[1]);
}
while((ch = getchar()) != EOF) {
printf("%c", decrypt(ch, key));
}
printf("\n");
break;
//Terminate Program :D
case 3:
printf("Terminating Caesar Cipher . . . Goodbye! :)");
exit(0);
break;
default:
printf("Not a valid entry. Please try again!\n\n");
}
}
return 0;
}