C
C#•2w ago
Faker

✅ How does CultureInfo works in C#?

Hello guys, it's been quite a few instances now that I came across CultureInfo. I encounted it when comparing strings and when comparing dates. What I understood about it is that, if we don't specify anything, it uses the locale system of our machine. So if our machine is set to en-us and we try to compare something with de-DE, their might be issues here? I know the "ß (Eszett)" stands for "ss" I think... so, what kind of issues might arise? If we write something like this for eg: 
C#
var str1 = "Grasse";
var str2 = "Graße"
if (str1 == str2) ...
C#
var str1 = "Grasse";
var str2 = "Graße"
if (str1 == str2) ...
str1 == str2 will return false in this case (If we don't change the CultureInfo thing)? Now there is also the CultureInfo when we use dates. This is where I'm the most confused. When we use methods like TryParse with DateOnly, it may happen that the overload contains the IFormatProvider interface, so basically these are "settings" to change the culture specific. For string I did understand what it does (but please someone confirm if the above statements are correct please.), for date, it's a bit ambiguous though. So say my locale system has culture en-us, basically, this mean that my date format is specific to the us culture. How will that affect my TryParse or TryParseExact?
7 Replies
Faker
FakerOP•2w ago
C#

string[] dates = ["22/01/2023","10/10/2022","12/31/2020","2020/10/10","2020/31/12"];
var l = new List<DateOnly>();
foreach (var d in dates)
{
    var success = DateOnly.TryParse(d,CultureInfo.InvariantCulture, out var temporaryDate);
    if (success) l.Add(temporaryDate);
}

foreach (var list in l)
{
    Console.WriteLine(list);
}

Output:
10/10/2022
12/31/2020
10/10/2020
C#

string[] dates = ["22/01/2023","10/10/2022","12/31/2020","2020/10/10","2020/31/12"];
var l = new List<DateOnly>();
foreach (var d in dates)
{
    var success = DateOnly.TryParse(d,CultureInfo.InvariantCulture, out var temporaryDate);
    if (success) l.Add(temporaryDate);
}

foreach (var list in l)
{
    Console.WriteLine(list);
}

Output:
10/10/2022
12/31/2020
10/10/2020
I tried the following code, I don't understand why only 3 dates are valid, what happen internally? Last question: 
C#

string[] dates = ["22/01/2023","10/10/2022","12/31/2020","2020/10/10","2020/31/12","20.10.2020"];
var l = new List<DateOnly>();

foreach (var d in dates)
{
    var success = DateOnly.TryParseExact(d,"dd.MM.yyyy",CultureInfo.InvariantCulture, DateTimeStyles.None ,out var temporaryDate);
    if (success) l.Add(temporaryDate);
}

foreach (var list in l)
{
    Console.WriteLine(list);
}
C#

string[] dates = ["22/01/2023","10/10/2022","12/31/2020","2020/10/10","2020/31/12","20.10.2020"];
var l = new List<DateOnly>();

foreach (var d in dates)
{
    var success = DateOnly.TryParseExact(d,"dd.MM.yyyy",CultureInfo.InvariantCulture, DateTimeStyles.None ,out var temporaryDate);
    if (success) l.Add(temporaryDate);
}

foreach (var list in l)
{
    Console.WriteLine(list);
}
Why is it important to put CultureInfo.InvariantCulture here? I obtain the following output only: 10/20/2020 meaning that we only look for the string with the format dd.MM.yyyy, so if we are already explicitly using a format, why make use of CultureInfo?
Angius
Angius•2w ago
Only 3 are valid, because "invariant" culture is basically "en-US" with some minor changes, like the currency symbol For ParseExact() the culture does not matter, because you are, well... parsing exactly
Faker
FakerOP•2w ago
oh ok make sense, because I don't see the importance of the culture info here if we are already providing the exact format, I don't see what additional things does it brings.... maybe it's useful in other of its overloads. When we use CultureInfo.Invariant, behind the scenes, it does use some default settings, like date formats, date separators, etc... ?
Angius
Angius•2w ago
Invariant culture simply defines some "generic" patterns, that are not supposed to be associated with any culture
MODiX
MODiX•2w ago
Angius
REPL Result: Success
using System.Globalization;                                                                                             Console.WriteLine(CultureInfo.InvariantCulture.DateTimeFormat.LongDatePattern);                                         Console.WriteLine(CultureInfo.InvariantCulture.Calendar.ToString());                                                    Console.WriteLine(CultureInfo.InvariantCulture.NumberFormat.CurrencySymbol);
using System.Globalization;                                                                                             Console.WriteLine(CultureInfo.InvariantCulture.DateTimeFormat.LongDatePattern);                                         Console.WriteLine(CultureInfo.InvariantCulture.Calendar.ToString());                                                    Console.WriteLine(CultureInfo.InvariantCulture.NumberFormat.CurrencySymbol);
Console Output
dddd, dd MMMM yyyy
System.Globalization.GregorianCalendar
¤
dddd, dd MMMM yyyy
System.Globalization.GregorianCalendar
¤
Compile: 402.596ms | Execution: 21.642ms | React with ❌ to remove this embed.
Angius
Angius•2w ago
There's more properties like that. Decimal separator, time format, and so on So, yes, you're correct here
Faker
FakerOP•2w ago
Yepp I see, it's clearer, I understand how all of that works now, thanks !!

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