new files

Task/Caesar-cipher/C/caesar-cipher.c

@@ -0,0 +1,36 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define caesar(x) rot(13, x)
+#define decaesar(x) rot(13, x)
+#define decrypt_rot(x, y) rot((26-x), y)
+
+void rot(int c, char *str)
+{
+	int l = strlen(str);
+	const char *alpha[2] = { "abcdefghijklmnopqrstuvwxyz", "ABCDEFGHIJKLMNOPQRSTUVWXYZ"};
+	
+	int i;
+	for (i = 0; i < l; i++)
+	{
+		if (!isalpha(str[i]))
+			continue;
+		
+		str[i] = alpha[isupper(str[i])][((int)(tolower(str[i])-'a')+c)%26];
+	}
+}
+
+
+int main()
+{
+	char str[] = "This is a top secret text message!";
+	
+	printf("Original: %s\n", str);
+	caesar(str);
+	printf("Encrypted: %s\n", str);
+	decaesar(str);
+	printf("Decrypted: %s\n", str);
+	
+	return 0;
+}