Convet Rational::Sub to - and -= operator overrides.

src/CalcManager/CEngine/Rational.cpp

@@ -114,20 +114,14 @@ namespace CalcEngine
         return *this;
     }
 
-    Rational operator+(Rational lhs, Rational const& rhs)
+    Rational& Rational::operator-=(Rational const& rhs)
-    {
-        lhs += rhs;
-        return lhs;
-    }
-
-    Rational Rational::Sub(Rational const& rhs, int32_t precision) const
     {
         PRAT lhsRat = this->ToPRAT();
         PRAT rhsRat = rhs.ToPRAT();
 
         try
         {
-            subrat(&lhsRat, rhsRat, precision);
+            subrat(&lhsRat, rhsRat, RATIONAL_PRECISION);
             destroyrat(rhsRat);
         }
         catch (DWORD error)
@@ -137,10 +131,22 @@ namespace CalcEngine
             throw(error);
         }
 
-        Rational result = Rational{ lhsRat };
+        *this = Rational{ lhsRat };
         destroyrat(lhsRat);
 
-        return result;
+        return *this;
+    }
+
+    Rational operator+(Rational lhs, Rational const& rhs)
+    {
+        lhs += rhs;
+        return lhs;
+    }
+
+    Rational operator-(Rational lhs, Rational const& rhs)
+    {
+        lhs -= rhs;
+        return lhs;
     }
 
     Rational Rational::Mul(Rational const& rhs, int32_t precision) const

src/CalcManager/CEngine/scicomm.cpp

@@ -727,7 +727,7 @@ void CCalcEngine::ProcessCommandWorker(WPARAM wParam)
     {
         /* MMINUS subtracts m_currentVal to immediate memory and kills the "mem"   */
         /* indicator if the result is zero.                           */
-        Rational result = m_memoryValue->Sub(m_currentVal, m_precision);
+        Rational result = *m_memoryValue - m_currentVal;
         m_memoryValue = make_unique<Rational>(TruncateNumForIntMath(result));
 
         break;

src/CalcManager/CEngine/scidisp.cpp

@@ -64,8 +64,7 @@ CalcEngine::Rational CCalcEngine::TruncateNumForIntMath(CalcEngine::Rational con
     if (result.IsLess(0, m_precision))
     {
         // if negative make positive by doing a twos complement
-        result = -(result);
+        result = -(result) - 1;
-        result = result.Sub(1, m_precision);
         result = result.Not(m_chopNumbers[m_numwidth], m_precision);
     }
 

src/CalcManager/CEngine/scifunc.cpp

@@ -182,14 +182,14 @@ CalcEngine::Rational CCalcEngine::SciCalcFunctions(CalcEngine::Rational const& r
 
                 Rational degreeRat = Integer(rat, m_precision);
 
-                Rational minuteRat = rat.Sub(degreeRat, m_precision);
+                Rational minuteRat = rat - degreeRat;
                 minuteRat = minuteRat.Mul(shftRat, m_precision);
 
                 Rational secondRat = minuteRat;
 
                 minuteRat = Integer(minuteRat, m_precision);
 
-                secondRat = secondRat.Sub(minuteRat, m_precision);
+                secondRat -= minuteRat;
                 secondRat = secondRat.Mul(shftRat, m_precision);
 
                 //

src/CalcManager/CEngine/scioper.cpp

@@ -69,7 +69,7 @@ CalcEngine::Rational CCalcEngine::DoOperation(int operation, CalcEngine::Rationa
             break;
 
         case IDC_SUB:
-            result = rhs.Sub(result, m_precision);
+            result = rhs - result;
             break;
 
         case IDC_MUL:

src/CalcManager/Header Files/Rational.h

@@ -31,12 +31,13 @@ namespace CalcEngine
 
         Rational operator-() const;
         Rational& operator+=(Rational const& rhs);
-        Rational Sub(Rational const& rhs, int32_t precision) const;
+        Rational& operator-=(Rational const& rhs);
         Rational Mul(Rational const& rhs, int32_t precision) const;
         Rational Div(Rational const& rhs, int32_t precision) const;
         Rational Mod(Rational const& rhs) const;
 
         friend Rational operator+(Rational lhs, Rational const& rhs);
+        friend Rational operator-(Rational lhs, Rational const& rhs);
 
         Rational Lsh(Rational const& r, int32_t precision) const;
         Rational Rsh(Rational const& r, int32_t precision) const;