diff --git a/04_UDEF/Testat/Testat.cpp b/04_UDEF/Testat/Testat.cpp
index e69de29..25bd4d7 100644
--- a/04_UDEF/Testat/Testat.cpp
+++ b/04_UDEF/Testat/Testat.cpp
@@ -0,0 +1,81 @@
+
+#include "../../helpers/println.hpp"
+#include <iostream>
+
+const int bitsPerOctet = 8;
+
+struct BinaryOctet {
+    bool evenParity;   // set to true if number of '1' in bitsAsDigits is even, false otherwise
+    char bitsAsDigits[bitsPerOctet]; // bit values as chars
+    BinaryOctet(int x = 0);
+
+    BinaryOctet(const BinaryOctet &) = default;
+};
+
+BinaryOctet::BinaryOctet(int x) {
+    int length = std::to_string(x).length() * 4;
+    while (x >= 1) {
+        bitsAsDigits[length] = (x % 2 == 0) ? '1' : '0';
+        x = x / 2;
+        length--;
+    }
+
+    int i = 0;
+    for (char c : bitsAsDigits) {
+        if (c == '1') i++;
+    }
+    evenParity = i % 2 == 0;
+}
+
+bool operator!=(BinaryOctet a, BinaryOctet b) {
+
+}
+
+BinaryOctet operator--(BinaryOctet &id, int) {
+
+}
+
+BinaryOctet operator+(BinaryOctet a, BinaryOctet b) {
+
+}
+
+BinaryOctet operator/(BinaryOctet a, BinaryOctet b) {
+
+}
+
+BinaryOctet doCalculation(BinaryOctet a, BinaryOctet b) {
+    BinaryOctet result;
+
+    for (; a != b; b--) {
+        a = a + 1;
+        a = a / b;
+    }
+    result = a + b;
+    return result;
+}
+
+// for println();
+std::string as_string(BinaryOctet a) {
+    std::string result = "(";
+    for (char c : a.bitsAsDigits) {
+        result += c;
+    }
+    result += ")";
+    return result;
+}
+
+// for std::cout
+/*std::ostream& operator<< (std::ostream& os, const BinaryOctet &toBePrinted){
+	os << "(" << ")";
+	return os;
+}*/
+
+int main(int argc, char **argv) {
+    BinaryOctet a = 0b00001111;
+    BinaryOctet b = 0b00000110;
+    println(new BinaryOctet(5));
+    println(new BinaryOctet(5));
+    //println("result = ", doCalculation(a,b));
+    //std::cout << "result = " << doCalculation(a,b) << std::endl;
+    return 0;
+}
diff --git a/04_UDEF/main_04_UDEF_a.cpp b/04_UDEF/main_04_UDEF_a.cpp
index 102c1ef..fd50ced 100644
--- a/04_UDEF/main_04_UDEF_a.cpp
+++ b/04_UDEF/main_04_UDEF_a.cpp
@@ -1,7 +1,6 @@
 // file: main_04_UDEF_a.cpp
 #include "../helpers/println.hpp"
 #include "RationalNumber.hpp"
-#include <iostream>
 
 // location 1