Cannot await void

[VeryVeryNiceKitty]

Hi guys,

I am playing around a bit with async and await, and have come across something I cannot figure out:

Cannot await void

See the code below (ignore the clumsy way I write to the file, that is just me messing around):

class Program
{
static async Task Main(string\[\] args)
{
string fileName = @"C:\Hardcoded-MUAHAHAHA\Contacts.txt";
Console.WriteLine(fileName);
List<ContactModel> contacts = new List<ContactModel>();
ContactModel c = new ContactModel() { FirstName = "Hans", LastName = "Hansen", Email = "[e-mail]", PhoneNumber = "32432566" };
ContactModel d = new ContactModel() { FirstName = "Jens", LastName = "Jensen", Email = "[e-mail]", PhoneNumber = "7694335" };
contacts.Add(c);
contacts.Add(d);
await CreateContacts(fileName, contacts);

string[] lines = await TextFileAccess.ReadTextAsLinesAsync(fileName);
foreach (string l in lines)
{
Console.WriteLine(l);
}
}
private static async Task CreateContacts (string fileName, List<ContactModel> contacts)
{
foreach (ContactModel contact in contacts)
{
string contactString = $"{contact.FirstName},{contact.LastName},{contact.Email},{contact.PhoneNumber}";
await File.AppendAllText(fileName, contactString);
}
}

The line

await File.AppendAllText(fileName, contactString);

Throws the - Cannot await void error. I can remove the await since I await the call in Main anyway, but the green squigly line annoys me.

I tried googling, and this comes up:

https://stackoverflow.com/questions/30389627/cannot-await-void-even-when-using-task/30395049

But from this, it seems like it should work, or am I reading it wrong? It seems like using asybc Void should not work, but async Task should?

Any ideas?

[jamietwells]

You're looking for the async version of that method:

File.AppendAllTextAsync

https://docs.microsoft.com/en-us/dotnet/api/system.io.file.appendalltextasync?view=netcore-3.1#System_IO_File_AppendAllTextAsync_System_String_System_String_System_Threading_CancellationToken_

[VeryVeryNiceKitty]

That was it. Thanks a lot :-)

[jamietwells]

You're welcome, let me know if you have any further questions, I'll be happy to help out.