'using' keyword before local variable declaration in C#?

Question

Hi I was going through some examples in C# and came across some code similar to below :

private void WriteData(string filePath)
{
    using var writer = new System.IO.StreamWriter(filePath);

    //Logic to write data here
}

I want to know what is the use and significance of using in variable declaration. Also how is it different from simple variable declaration :

var writer = new System.IO.StreamWriter(filePath);

you might want to look at https://stackoverflow.com/questions/75401/what-are-the-uses-of-using-in-c# — Athul Raj, Jul 10 '20 at 11:33
@LasseV.Karlsen it's accepted answer shows the new style aswell — Athul Raj, Jul 10 '20 at 11:37

score 3 · Accepted Answer · answered Jul 10 '20 at 11:33

It is a C# 8 syntax sugar for a traditional using statement which ensures that Dispose() method will be called for a type implementing IDisposable interface.

See https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/using-statement#example

'using' keyword before local variable declaration in C#?

1 Answers1