#include <iostream>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int main()
{
	printf("Bitte Zeichenkette eingeben: ");
	char stringPlain[100];
	gets_s(stringPlain);

	printf("Bitte Key eingeben: ");
	char key[100];
	gets_s(key);

	char stringEncoded[100] = "";
	int keyCounter = 0;

	//toLowerCase
	for (int i = 0; i < strlen(stringPlain); i++) {
		if (stringPlain[i] >= 65 && stringPlain[i] <= 90) {
			stringPlain[i] += 32;
		}
	}
	printf("Nicht verschluesselt: %s \n", stringPlain);

	for (int i = 0; i < strlen(stringPlain); i++) {
		if (stringPlain[i] >= 97 && stringPlain[i] <= 122) {
			if (keyCounter > 2) {
				keyCounter = 0;
			}
			stringEncoded[i] = ((stringPlain[i] - 'a' + key[keyCounter] - 'A') % 26) + 'a';
			keyCounter++;
		}
		else {
			stringEncoded[i] = stringPlain[i];
		}
	}
	printf("Verschluesselt: %s \n", stringEncoded);
}