Skip to content

Support the F, N, E, R and G<n> standard format strings [patch] #170

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
matt-edmondson merged 2 commits into from
Oct 12, 2026
Merged

Support the F, N, E, R and G<n> standard format strings [patch] #170

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
2e33e4d
Support the F, N, E, R and G<n> standard format strings [patch]
claude Oct 12, 2026
449bec3
Split fixed-point formatting helpers and use Assert.Contains [patch]
claude Oct 12, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
111 changes: 104 additions & 7 deletions PreciseNumber.Test/PreciseNumberTests.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1523,7 +1523,9 @@ public void TestTryFormatEmptyFormat()
public void TestTryFormatInvalidFormat()
{
PreciseNumber number = PreciseNumber.CreateFromComponents(-2, 12345);
Assert.ThrowsExactly<FormatException>(() => number.TryFormat(stackalloc char[50], out int charsWritten, "e", CultureInfo.InvariantCulture));
FormatException exception = Assert.ThrowsExactly<FormatException>(() => number.TryFormat(stackalloc char[50], out int charsWritten, "0.00", CultureInfo.InvariantCulture));
Assert.Contains("'0.00'", exception.Message);
Assert.Contains("F, N and E", exception.Message);
}

[TestMethod]
Expand Down Expand Up @@ -1731,18 +1733,113 @@ public void TestHandlingTrailingZeros()
public void TestToStringVariousFormats()
{
PreciseNumber number = PreciseNumber.CreateFromComponents(-2, 12345);
Assert.ThrowsExactly<FormatException>(() => number.ToString("E2", CultureInfo.InvariantCulture));
Assert.ThrowsExactly<FormatException>(() => number.ToString("F2", CultureInfo.InvariantCulture));
Assert.ThrowsExactly<FormatException>(() => number.ToString("N2", CultureInfo.InvariantCulture));
Assert.AreEqual("1.23E+002", number.ToString("E2", CultureInfo.InvariantCulture));
Assert.AreEqual("123.45", number.ToString("F2", CultureInfo.InvariantCulture));
Assert.AreEqual("123.45", number.ToString("N2", CultureInfo.InvariantCulture));
}

[TestMethod]
public void TestTryFormatVariousFormats()
{
PreciseNumber number = PreciseNumber.CreateFromComponents(-2, 12345);
Assert.ThrowsExactly<FormatException>(() => number.TryFormat(stackalloc char[50], out int charsWritten, "E2".AsSpan(), CultureInfo.InvariantCulture));
Assert.ThrowsExactly<FormatException>(() => number.TryFormat(stackalloc char[50], out int charsWritten, "F2".AsSpan(), CultureInfo.InvariantCulture));
Assert.ThrowsExactly<FormatException>(() => number.TryFormat(stackalloc char[50], out int charsWritten, "N2".AsSpan(), CultureInfo.InvariantCulture));
Span<char> buffer = stackalloc char[50];
Assert.IsTrue(number.TryFormat(buffer, out int charsWritten, "E2".AsSpan(), CultureInfo.InvariantCulture));
Assert.AreEqual("1.23E+002", buffer[..charsWritten].ToString());
Assert.IsTrue(number.TryFormat(buffer, out charsWritten, "F1".AsSpan(), CultureInfo.InvariantCulture));
Assert.AreEqual("123.5", buffer[..charsWritten].ToString());
Assert.IsTrue(number.TryFormat(buffer, out charsWritten, "N2".AsSpan(), CultureInfo.InvariantCulture));
Assert.AreEqual("123.45", buffer[..charsWritten].ToString());
}

[TestMethod]
public void TestTryFormatStandardFormatReturnsFalseWhenDestinationTooSmall()
{
PreciseNumber number = PreciseNumber.CreateFromComponents(-2, 12345);
Assert.IsFalse(number.TryFormat(stackalloc char[5], out int charsWritten, "F2".AsSpan(), CultureInfo.InvariantCulture));
Assert.AreEqual(0, charsWritten);
}

[TestMethod]
[DataRow("1234.5678", "F2", "1234.57")]
[DataRow("1234.5678", "F0", "1235")]
[DataRow("1234.5", "F3", "1234.500")]
[DataRow("0.005", "F2", "0.01")]
[DataRow("-0.004", "F2", "0.00")]
[DataRow("-1.005", "F2", "-1.01")]
[DataRow("0.0001", "F6", "0.000100")]
[DataRow("12000", "F1", "12000.0")]
[DataRow("1234.5", "F", "1234.50")]
[DataRow("0", "F2", "0.00")]
[DataRow("1234567.891", "N2", "1,234,567.89")]
[DataRow("-1234567.891", "N0", "-1,234,568")]
[DataRow("999.995", "N2", "1,000.00")]
[DataRow("123", "N2", "123.00")]
[DataRow("1234.5678", "E5", "1.23457E+003")]
[DataRow("1234.5678", "e2", "1.23e+003")]
[DataRow("-0.00012345", "E3", "-1.235E-004")]
[DataRow("9.9999", "E2", "1.00E+001")]
[DataRow("5", "E0", "5E+000")]
[DataRow("0", "E2", "0.00E+000")]
[DataRow("12", "E", "1.200000E+001")]
[DataRow("1234.5678", "R", "1234.5678")]
[DataRow("1234.5678", "r", "1234.5678")]
[DataRow("1234.5678", "G5", "1234.6")]
[DataRow("1234.5678", "G0", "1234.5678")]
public void TestToStringStandardFormats(string value, string format, string expected)
{
PreciseNumber number = PreciseNumber.Parse(value, CultureInfo.InvariantCulture);
Assert.AreEqual(expected, number.ToString(format, CultureInfo.InvariantCulture));
}

[TestMethod]
public void TestInterpolatedFixedPointFormat()
{
PreciseNumber number = PreciseNumber.Parse("3.14159", CultureInfo.InvariantCulture);
Assert.AreEqual("Value: 3.14", string.Create(CultureInfo.InvariantCulture, $"Value: {number:F2}"));
Assert.AreEqual("3.14", string.Format(CultureInfo.InvariantCulture, "{0:N2}", number));
}

[TestMethod]
public void TestStandardFormatsUseCultureSeparators()
{
PreciseNumber number = PreciseNumber.Parse("-1234567.891", CultureInfo.InvariantCulture);
NumberFormatInfo german = (NumberFormatInfo)CultureInfo.InvariantCulture.NumberFormat.Clone();
german.NumberDecimalSeparator = ",";
german.NumberGroupSeparator = ".";
Assert.AreEqual("-1.234.567,89", number.ToString("N2", german));
Assert.AreEqual("-1234567,89", number.ToString("F2", german));
Assert.AreEqual("-1,23E+006", number.ToString("E2", german));
}

[TestMethod]
public void TestNumberFormatHonoursGroupSizesAndNegativePattern()
{
NumberFormatInfo numberFormat = (NumberFormatInfo)CultureInfo.InvariantCulture.NumberFormat.Clone();
numberFormat.NumberGroupSizes = [3, 2];
numberFormat.NumberNegativePattern = 0;
PreciseNumber number = PreciseNumber.Parse("-123456789", CultureInfo.InvariantCulture);
Assert.AreEqual("(12,34,56,789)", number.ToString("N0", numberFormat));
}

[TestMethod]
public void TestScientificFormatReachesTinyExponentsWithoutFixedPointExpansion()
{
PreciseNumber number = PreciseNumber.CreateFromComponents(-1000000, 1);
Assert.AreEqual("1.00E-1000000", number.ToString("E2", CultureInfo.InvariantCulture));
}

[TestMethod]
[DataRow("0.00")]
[DataRow("#,##0")]
[DataRow("X")]
[DataRow("C2")]
[DataRow("R2")]
[DataRow("F1000000000")]
public void TestToStringUnsupportedFormatThrowsDescriptiveFormatException(string format)
{
PreciseNumber number = PreciseNumber.CreateFromComponents(-2, 12345);
FormatException exception = Assert.ThrowsExactly<FormatException>(() => number.ToString(format, CultureInfo.InvariantCulture));
Assert.Contains(format, exception.Message);
}

[TestMethod]
Expand Down
Loading
Loading