From 2e778ff3f4ab75002c4edbca709e842c42c6c0c0 Mon Sep 17 00:00:00 2001
From: Tobias Berger <berger@edv-ermtraud.net>
Date: Tue, 21 Sep 2021 11:40:44 +0200
Subject: [PATCH] inv, more errors (for pow in future), toDouble and toFloat
 (untested)

---
 fraction.cpp         |  6 ++++++
 fraction.hpp         | 11 +++++++----
 tst_fractiontest.cpp | 21 ++++++++++++++++++++-
 3 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/fraction.cpp b/fraction.cpp
index 2a6c09d..51df04f 100644
--- a/fraction.cpp
+++ b/fraction.cpp
@@ -70,6 +70,12 @@ namespace FractionNS {
   QString Fraction::display() const {
     return QString::number(m_numerator) + '/' + QString::number(m_denominator);
   }
+  Fraction& Fraction::inv() const {
+    return *new Fraction(m_denominator, m_numerator);
+  }
+
+  float Fraction::toFloat() const { return float(m_numerator) / m_denominator; }
+  double Fraction::toDouble() const { return double(m_numerator) / m_denominator; }
 
   bool Fraction::operator==(const int n) const {
     return (double(m_numerator) / double(m_denominator)) == n;
diff --git a/fraction.hpp b/fraction.hpp
index ac988c4..6f6dcb1 100644
--- a/fraction.hpp
+++ b/fraction.hpp
@@ -3,10 +3,9 @@
 #include <QString>
 
 namespace FractionNS {
-  class divide_by_zero_error : public std::logic_error {
-  public:
-    divide_by_zero_error() : std::logic_error("tried to divide by zero") {};
-  };
+  struct divide_by_zero_error : public std::logic_error { divide_by_zero_error() : std::logic_error("tried to divide by zero") {}; };
+  struct not_real_error : public std::logic_error { not_real_error() : std::logic_error("value is not a real number") {}; };
+  struct not_defined_error : public std::logic_error { not_defined_error() : std::logic_error("operation result is not defined") {}; };
 
   class Fraction
   {
@@ -26,6 +25,10 @@ namespace FractionNS {
     void setDenominator(const int);
 
     QString display() const;
+    Fraction& inv() const;
+
+    float toFloat() const;
+    double toDouble() const;
 
     // Binary comparison operators
     bool operator==(const int) const;
diff --git a/tst_fractiontest.cpp b/tst_fractiontest.cpp
index 57fc24c..228f174 100644
--- a/tst_fractiontest.cpp
+++ b/tst_fractiontest.cpp
@@ -28,9 +28,12 @@ private slots:
   void test_greater_than();
   void test_less_than_or_equal();
   void test_greater_than_or_equal();
+  void test_inverse();
 };
 
-FractionTest::FractionTest() {};
+FractionTest::FractionTest() {
+  qDebug();
+};
 FractionTest::~FractionTest() {};
 
 void FractionTest::test_constructor() {
@@ -423,6 +426,22 @@ void FractionTest::test_greater_than_or_equal() {
 
 }
 
+void FractionTest::test_inverse() {
+  const Fraction f1 = Fraction(3, 2);
+  const Fraction f2 = Fraction(2, 3);
+  QCOMPARE(f1.inv(), f2);
+  QCOMPARE(f2.inv(), f1);
+
+  const Fraction f3 = Fraction(0, 2);
+  bool threw_divide_by_zero_error = false;
+  try {
+    f3.inv();
+  }  catch (const divide_by_zero_error&) {
+    threw_divide_by_zero_error = true;
+  }
+  QVERIFY(threw_divide_by_zero_error);
+}
+
 QTEST_APPLESS_MAIN(FractionTest)
 
 #include "tst_fractiontest.moc"