restructure and add ipi texs

ws2019/ipi/uebungen/cpp_headers/Rational2.cc

@@ -0,0 +1,72 @@
+#include "fcpp.hh"
+
+struct Rational {
+  int zaehler;
+  int nenner;
+} ;
+
+// Abstraktion: Konstruktor und Selektoren
+
+Rational erzeuge_rat (int z, int n)
+{
+  Rational t;
+  t.zaehler = z;
+  t.nenner = n;
+  return t;
+}
+
+int zaehler (Rational q)
+{
+  return q.zaehler;
+}
+
+int nenner (Rational q)
+{
+  return q.nenner;
+}
+
+// Arithmetische Operationen
+
+Rational add_rat (Rational p, Rational q)
+{
+  return erzeuge_rat(
+    zaehler(p)*nenner(q)+zaehler(q)*nenner(p),
+    nenner(p)*nenner(q));
+}
+
+Rational sub_rat (Rational p, Rational q)
+{
+  return erzeuge_rat(
+    zaehler(p)*nenner(q)-zaehler(q)*nenner(p),
+    nenner(p)*nenner(q));
+}
+
+Rational mul_rat (Rational p, Rational q)
+{
+  return erzeuge_rat(zaehler(p)*zaehler(q),
+		     nenner(p)*nenner(q));
+}
+
+Rational div_rat (Rational p, Rational q)
+{
+  return erzeuge_rat(zaehler(p)*nenner(q),
+		     nenner(p)*zaehler(q));
+}
+
+void drucke_rat (Rational p)
+{
+  print(zaehler(p),"/",nenner(p),0);
+}
+
+int main ()
+{
+  Rational p = erzeuge_rat(3,4);
+  Rational q = erzeuge_rat(5,3);
+  drucke_rat(p); drucke_rat(q);
+    
+  // p*q+p-p*p
+  Rational r = sub_rat(add_rat(mul_rat(p,q), p),
+		       mul_rat(p,p));
+  drucke_rat(r);
+  return 0;
+}