Culture specific strings with String.Create

Daily Knowledge Drop

Introduced in C# 10 (.NET 6), the String.Create method can be used to evaluate an interpolated string to a specific culture (including the invariant culture). This method is faster, and uses less resources than the previously available method of using FormattableString.

FormattableString

Invariant

Prior to C# 10 FormattableString was the method used, and evaluating an interpolated string to invariant culture was fairly straightforward:

private decimal decValue = 1.99m;
private DateTime dateValue = DateTime.UtcNow;

// output the default interpolated string
Console.WriteLine($"Decimal: {decValue} | Date: {dateValue}");

// output the string formatted to "invariant culture"
Console.WriteLine(FormattableString.Invariant(
    $"Decimal: {decValue} | Date: {dateValue}"));

The output of the above:

Decimal: 1,99 | Date: 2022/09/12 03:49:41
Decimal: 1.99 | Date: 09/12/2022 03:49:41

Culture specific

Evaluating an interpolated string to a specific culture is slightly more complicated when using FormattableString:

private decimal decValue = 1.99m;
private DateTime dateValue = DateTime.UtcNow;

// output the default interpolated string
Console.WriteLine($"Decimal: {decValue} | Date: {dateValue}");

// output the string formatted in the specific culture
// first declare the FormattableString
FormattableString formattable = $"Decimal: {decValue} | Date: {dateValue}";
// ToString specifying the culture
Console.Write(formattable.ToString(CultureInfo.GetCultureInfo("en-US")));

The output of the above:

Decimal: 1,99 | Date: 2022/09/12 04:00:47
Decimal: 1.99 | Date: 9/12/2022 4:00:47 AM

String.Create

Invariant

The new String.Create method introduced in .NET6 with C# 10, simplifies the evaluation of a interpolated string to a specific culture:

private decimal decValue = 1.99m;
private DateTime dateValue = DateTime.UtcNow;

// output the default interpolated string
Console.WriteLine($"Decimal: {decValue} | Date: {dateValue}");

// output string with the specific culture (invariant)
Console.WriteLine(String.Create(CultureInfo.InvariantCulture,
    $"Decimal: {decValue} | Date: {dateValue}"));

The output of the above (which is the same as when using FormattableString.Invariant above):

Decimal: 1,99 | Date: 2022/09/12 04:02:59
Decimal: 1.99 | Date: 09/12/2022 04:02:59

Culture specific

Specifying a specific culture with String.Create is just as simple as specifying InvariantCulture, and definitely simpler than the FormattableString equivalent:

private decimal decValue = 1.99m;
private DateTime dateValue = DateTime.UtcNow;

// output the default interpolated string
Console.WriteLine($"Decimal: {decValue} | Date: {dateValue}");

// output string with the specific culture (en-US)
Console.WriteLine(String.Create(CultureInfo.GetCultureInfo("en-US"),
    $"Decimal: {decValue} | Date: {dateValue}"));

The output of the above (which is the same as when using FormattableString with the specific culture above):

Decimal: 1,99 | Date: 2022/09/12 04:05:15
Decimal: 1.99 | Date: 9/12/2022 4:05:15 AM

Performance

Using BenchmarkDotNet to compare the speed and memory usage of the above 4 methods, we can see that in all cases, using the String.Create version is faster, and uses less memory than the FormattableString versions:

Notes

Even though the performance and memory improvements are slight (nano-seconds and bytes), if your application is making heavy use of FormattableString to format strings to specific cultures, then there are gains to be had by converting to using String.Create.

References

Performance: string.Create vs FormattableString

Daily Drop 176: 06-10-2022

At the start of 2022 I set myself the goal of learning one new coding related piece of knowledge a day.
It could be anything - some.NET / C# functionality I wasn't aware of, a design practice, a cool new coding technique, or just something I find interesting. It could be something I knew at one point but had forgotten, or something completely new, which I may or may never actually use.

The Daily Drop is a record of these pieces of knowledge - writing about and summarizing them helps re-enforce the information for myself, as well as potentially helps others learn something new as well.