From 75fde82f4613d5fe63e2fb2ddc2e57c80309933b Mon Sep 17 00:00:00 2001
From: Rudy Huyn <rudyhuyn@gmail.com>
Date: Mon, 1 Jun 2020 16:50:45 -0700
Subject: [PATCH] Fix how we calculate the precision in Unit converter and
 update GetNumberDigitsWholeNumberPart  (#1256)

* Fix 1255

* optimization

* spacing
---
 src/CalcManager/NumberFormattingUtils.cpp         | 2 +-
 src/CalcManager/UnitConverter.cpp                 | 3 ++-
 src/CalculatorUnitTests/CalculatorManagerTest.cpp | 4 ++++
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/CalcManager/NumberFormattingUtils.cpp b/src/CalcManager/NumberFormattingUtils.cpp
index f535cecb..63563972 100644
--- a/src/CalcManager/NumberFormattingUtils.cpp
+++ b/src/CalcManager/NumberFormattingUtils.cpp
@@ -50,7 +50,7 @@ namespace CalcManager::NumberFormattingUtils
     /// <param name="value">the number</param>
     unsigned int GetNumberDigitsWholeNumberPart(double value)
     {
-        return value == 0 ? 1 : (1 + static_cast<unsigned int>(log10(abs(value))));
+        return value == 0 ? 1u : static_cast<unsigned int>(1 + max(0.0, log10(abs(value))));
     }
 
     /// <summary>
diff --git a/src/CalcManager/UnitConverter.cpp b/src/CalcManager/UnitConverter.cpp
index f7a413b7..ec85e57b 100644
--- a/src/CalcManager/UnitConverter.cpp
+++ b/src/CalcManager/UnitConverter.cpp
@@ -905,7 +905,8 @@ void UnitConverter::Calculate()
                 {
                     // Fewer digits are needed following the decimal if the number is large,
                     // we calculate the number of decimals necessary based on the number of digits in the integer part.
-                    precision = max(0U, max(OPTIMALDIGITSALLOWED, min(MAXIMUMDIGITSALLOWED, currentNumberSignificantDigits)) - numPreDecimal);
+                    auto numberDigits = max(OPTIMALDIGITSALLOWED, min(MAXIMUMDIGITSALLOWED, currentNumberSignificantDigits));
+                    precision = numberDigits > numPreDecimal ? numberDigits - numPreDecimal : 0;
                 }
 
                 m_returnDisplay = RoundSignificantDigits(returnValue, precision);
diff --git a/src/CalculatorUnitTests/CalculatorManagerTest.cpp b/src/CalculatorUnitTests/CalculatorManagerTest.cpp
index ab8e83e8..eb726405 100644
--- a/src/CalculatorUnitTests/CalculatorManagerTest.cpp
+++ b/src/CalculatorUnitTests/CalculatorManagerTest.cpp
@@ -970,6 +970,10 @@ namespace CalculatorManagerTest
         VERIFY_ARE_EQUAL(digitsCount, 15);
         digitsCount = GetNumberDigitsWholeNumberPart(324328412837382.232213214324234);
         VERIFY_ARE_EQUAL(digitsCount, 15);
+        digitsCount = GetNumberDigitsWholeNumberPart(0.032);
+        VERIFY_ARE_EQUAL(digitsCount, 1);
+        digitsCount = GetNumberDigitsWholeNumberPart(0.00000000000000000001);
+        VERIFY_ARE_EQUAL(digitsCount, 1);
     }
 
     void CalculatorManagerTest::CalculatorManagerNumberFormattingUtils_RoundSignificantDigits()