fix Ut8Formatter when formatting floating-point whole number

Hexa.NET.Utilities.Tests/Utf8FormatterTests.cs

@@ -0,0 +1,100 @@
+using System.Globalization;
+using System.Text;
+using Hexa.NET.Utilities.Text;
+
+namespace Hexa.NET.Utilities.Tests;
+
+public class Utf8FormatterTests
+{
+    [TestCase(1f, 0, "1")]
+    [TestCase(10f, 0, "10")]
+    [TestCase(0.5f, 1, "0.5")]
+    [TestCase(0.75f, 2, "0.75")]
+    [TestCase(0.125f, 3, "0.125")]
+    [TestCase(0.0625f, 4, "0.0625")]
+    [TestCase(0.03125f, 5, "0.03125")]
+    [TestCase(0.015625f, 6, "0.015625")]
+    [TestCase(0.0078125f, 7, "0.0078125")]
+    public unsafe void FormatFloatTest(float value, int digit, string expected)
+    {
+        // Arrange
+        byte* buffer = stackalloc byte[128];
+
+        // Act
+        int len = Utf8Formatter.Format(value, buffer, 128, CultureInfo.InvariantCulture, digit);
+        ReadOnlySpan<byte> utf8Span = new ReadOnlySpan<byte>(buffer, len);
+
+        // Assert
+        Assert.That(Encoding.UTF8.GetString(utf8Span), Is.EqualTo(expected));
+    }
+
+    [TestCase(1, 0, "1")]
+    [TestCase(10, 0, "10")]
+    [TestCase(0.5, 1, "0.5")]
+    [TestCase(0.75, 2, "0.75")]
+    [TestCase(0.125, 3, "0.125")]
+    [TestCase(0.0625, 4, "0.0625")]
+    [TestCase(0.03125, 5, "0.03125")]
+    [TestCase(0.015625, 6, "0.015625")]
+    [TestCase(0.0078125, 7, "0.0078125")]
+    public unsafe void FormatDoubleTest(double value, int digit, string expected)
+    {
+        // Arrange
+        byte* buffer = stackalloc byte[128];
+
+        // Act
+        int len = Utf8Formatter.Format(value, buffer, 128, CultureInfo.InvariantCulture, digit);
+        ReadOnlySpan<byte> utf8Span = new ReadOnlySpan<byte>(buffer, len);
+
+        // Assert
+        Assert.That(Encoding.UTF8.GetString(utf8Span), Is.EqualTo(expected));
+    }
+
+    [TestCase(10, 0, ".","10")]
+    [TestCase(10, 0, "\uFF0C","10")]
+    [TestCase(0.75f, 2, ".","0.75")]
+    [TestCase(0.75f, 2, "\uFF0C","0\uFF0C75")]
+    public unsafe void FormatFloatCultureTest(float value, int digit, string separator, string expected)
+    {
+        // Arrange
+        byte* buffer = stackalloc byte[128];
+        var culture = new CultureInfo( "", false )
+        {
+            NumberFormat =
+            {
+                CurrencyDecimalSeparator = separator
+            }
+        };
+
+        // Act
+        int len = Utf8Formatter.Format(value, buffer, 128, culture, digit);
+        ReadOnlySpan<byte> utf8Span = new ReadOnlySpan<byte>(buffer, len);
+
+        // Assert
+        Assert.That(Encoding.UTF8.GetString(utf8Span), Is.EqualTo(expected));
+    }
+
+    [TestCase(10, 0, ".","10")]
+    [TestCase(10, 0, "\uFF0C","10")]
+    [TestCase(0.75, 2, ".","0.75")]
+    [TestCase(0.75, 2, "\uFF0C","0\uFF0C75")]
+    public unsafe void FormatDoubleCultureTest(double value, int digit, string separator, string expected)
+    {
+        // Arrange
+        byte* buffer = stackalloc byte[128];
+        var culture = new CultureInfo( "", false )
+        {
+            NumberFormat =
+            {
+                CurrencyDecimalSeparator = separator
+            }
+        };
+
+        // Act
+        int len = Utf8Formatter.Format(value, buffer, 128, culture, digit);
+        var utf8Span = new ReadOnlySpan<byte>(buffer, len);
+
+        // Assert
+        Assert.That(Encoding.UTF8.GetString(utf8Span), Is.EqualTo(expected));
+    }
+}

Hexa.NET.Utilities/Text/Utf8Formatter.cs

@@ -326,7 +326,9 @@ public static unsafe int Format(float value, byte* buffer, int bufSize, CultureI
                 return (int)(buffer - start);
             }
 
+            byte* beforeSeparator = buffer;
             buffer += ConvertUtf16ToUtf8(format.CurrencyDecimalSeparator, buffer, (int)(end - buffer));
+            byte* afterSeparator = buffer;
 
             digits = digits >= 0 ? digits : 7;
 
@@ -340,11 +342,16 @@ public static unsafe int Format(float value, byte* buffer, int bufSize, CultureI
                 if (fraction < 1e-14) break;
             }
 
-            while (*(buffer - 1) == '0' || *(buffer - 1) == '.')
+            while (buffer != afterSeparator && *(buffer - 1) == '0')
             {
                 buffer--;
             }
 
+            if (buffer == afterSeparator)
+            {
+                buffer = beforeSeparator;
+            }
+
         end:
             *buffer = 0;
             return (int)(buffer - start);
@@ -404,7 +411,9 @@ public static unsafe int Format(double value, byte* buffer, int bufSize, Culture
                 return (int)(buffer - start);
             }
 
+            byte* beforeSeparator = buffer;
             buffer += ConvertUtf16ToUtf8(format.CurrencyDecimalSeparator, buffer, (int)(end - buffer));
+            byte* afterSeparator = buffer;
 
             digits = digits >= 0 ? digits : 7;
 
@@ -418,11 +427,16 @@ public static unsafe int Format(double value, byte* buffer, int bufSize, Culture
                 if (fraction < 1e-14) break;
             }
 
-            while (*(buffer - 1) == '0' || *(buffer - 1) == '.')
+            while (buffer != afterSeparator && *(buffer - 1) == '0')
             {
                 buffer--;
             }
 
+            if (buffer == afterSeparator)
+            {
+                buffer = beforeSeparator;
+            }
+
         end:
             *buffer = 0;
             return (int)(buffer - start);