Also multiplication

cnumber.cpp

@@ -3,8 +3,9 @@
 
 
 int main() {
-	cnumber a(-1, 4);
+	cnumber a(1, -3);
-	cnumber b(4, -7);
+	cnumber b(2, 5);
 
 	cout << "a = " << a << " b = " <<  b << " a + b =  " << a + b << endl;
+	cout << "a = " << a << " b = " <<  b << " a * b =  " << a * b << endl;
 }

cnumber.hpp

@@ -22,6 +22,10 @@ class cnumber {
 			cnumber z(that.r + this->r, that.i + this->i);
 			return z;
 		}
+		cnumber operator*(const cnumber &that) {
+			cnumber z( (that.r * this->r ) - (that.i * this->i) , (that.r * this->i) + (this->r * that.i) );
+			return z;
+		}
 
 		friend ostream &operator<<( ostream &os, const cnumber &z ) { 
 			os << z.r << (z.signi ? '+' : '\0' ) <<  z.i << 'i';