addition full adder base case 0+0=0 with carryover

src/addition.c

@@ -2,5 +2,5 @@
 #include <stdlib.h>
 
 void volladdierer (int* s, int* nc, int a, int b, int c) {
-    s[0] = 0;
+    s[0] = c;
 }