From 2bd38e44ba6eeab1f8ba7d25024a769c6df67452 Mon Sep 17 00:00:00 2001
From: Mike Buland <mike@xagasoft.com>
Date: Wed, 17 Apr 2013 20:52:57 -0600
Subject: You can now add and subtract fractional numbers.

---
 src/main.cpp   |  1 +
 src/number.cpp | 53 +++++++++++++++++++++++++++++++++++------------------
 2 files changed, 36 insertions(+), 18 deletions(-)

(limited to 'src')

diff --git a/src/main.cpp b/src/main.cpp
index 1499285..061ebbb 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -284,6 +284,7 @@ void fractest()
     println("%1").arg( a );
     b = "0.987";
     println("%1 + %2 = %3").arg( a ).arg( b ).arg( a + b );
+    println("%1 - %2 = %3").arg( a ).arg( b ).arg( a - b );
 }
 
 int main( int , char *[] )
diff --git a/src/number.cpp b/src/number.cpp
index 49e8a60..9fd3865 100644
--- a/src/number.cpp
+++ b/src/number.cpp
@@ -332,6 +332,13 @@ Bu::String Number::toString() const
 
 int Number::digit( int iIdx ) const
 {
+    if( iIdx < 0 )
+    {
+        if( iIdx <= -iScale )
+            return 0;
+        else
+            return aFrac[-1-iIdx];
+    }
     if( iIdx >= aInt.getSize() )
         return 0;
     return aInt[iIdx];
@@ -350,21 +357,26 @@ Number Number::add( const Number &rhs, bool bSub ) const
     if( bPositive == (bSub?!rhs.bPositive:rhs.bPositive))
     {
         ret.bPositive = bPositive;
-        for( int j = 0; j < iPlaces || iCarry > 0; j++ )
+        for( int j = 1-iScale; j < iPlaces || iCarry > 0; j++ )
         {
             int iRes = iCarry + digit( j ) + rhs.digit( j );
-//            Bu::println(" Place: %1 + %2 + (%3) = %4").
+//            Bu::println(" [%5] Place: %1 + %2 + (%3) = %4").
 //                arg( digit(j) ).arg( rhs.digit( j ) ).arg( iCarry )
-//                .arg( iRes );
-            if( iRes == 0 )
+//                .arg( iRes ).arg( j );
+            if( j < 0 )
+                ret.aFrac.set( -1-j, (iRes%iRadix) );
+            else
             {
-                iZeros++;
-                continue;
+                if( iRes == 0 )
+                {
+                    iZeros++;
+                    continue;
+                }
+                for(; iZeros > 0; iZeros-- )
+                    ret.aInt.append( 0 );
+                
+                ret.aInt.append( (iRes%iRadix) );
             }
-            for(; iZeros > 0; iZeros-- )
-                ret.aInt.append( 0 );
-            
-            ret.aInt.append( (iRes%iRadix) );
             if( iRes < iRadix )
                 iCarry = 0;
             else
@@ -378,21 +390,26 @@ Number Number::add( const Number &rhs, bool bSub ) const
         ret.bPositive = bPositive;
         int iRes;
         int iComp = (iRadix-1);
-        for( int j = 0; j < iPlaces; j++ )
+        for( int j = 1-iScale; j < iPlaces; j++ )
         {
             iRes = digit( j ) + (iComp-rhs.digit( j )) + iCarry;
 //            Bu::println(" Place: %1 + %2 + (%3) = %4").
 //                arg( digit(j) ).arg( 9-rhs.digit( j ) ).arg( iCarry )
 //                .arg( iRes );
-            if( iRes == 0 )
+            if( j < 0 )
+                ret.aFrac.set( -1-j, (iRes%iRadix) );
+            else
             {
-                iZeros++;
-                continue;
-            }
-            for(; iZeros > 0; iZeros-- )
-                ret.aInt.append( 0 );
+                if( iRes == 0 )
+                {
+                    iZeros++;
+                    continue;
+                }
+                for(; iZeros > 0; iZeros-- )
+                    ret.aInt.append( 0 );
 
-            ret.aInt.append( (iRes%iRadix) );
+                ret.aInt.append( (iRes%iRadix) );
+            }
             if( iRes < iRadix )
                 iCarry = 0;
             else
-- 
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