c# var

[Davyd McColl]

Apart from the obvious (it saves typing and you have a set maximum number of keystrokes you can make in your life), it also allows for alignment which makes things easier to read (we're better with vertical scanning than horizontal scanning - for more see: https://www.youtube.com/watch?v=ZsHMHukIlJY and also there's just plain less to read!) but also because consuming code is more likely to survive a refactor intact: changing return type to something with similar shape means no consumer changes, renames of classes don't have to alter as many lines of code. Since it's syntactic sugar, it costs nothing at runtime and it's normally one of the first automated fixes I do in a file when I enter legacy code.

------------------------------------------------ If you say that getting the money is the most important thing You will spend your life completely wasting your time You will be doing things you don't like doing In order to go on living That is, to go on doing things you don't like doing Which is stupid. - Alan Watts https://www.youtube.com/watch?v=-gXTZM\_uPMY

[salz150]

I've read that convention is to use "var" when the type of variable is apparent by reading the code. If you printed out this code it would still be pretty obvious that "url" is a string. If you can't tell the type by reading the code then the actual type should be used. It is lazy but if it eliminates some redundancy and makes coding a little quicker than it's a good thing. I personally follow the convention above but I know some people use var for everything.

[User 2893688]

Actually your example is quite interesting, as it isn't really a String but rather Uri. The correct way to declare it would have been

using System;

...
Uri url = new Uri("http://www.contoso.com/");

WebRequest wr = WebRequest.Create(siteUri);

But as you might have figured, you could have just used this instead

var url = new Uri("http://www.contoso.com/");

var wr = WebRequest.Create(siteUri);

or just

var url = "http:// www. contoso.com/";
var request = WebRequest.Create (url);

[ZurdoDev]

Member 2896020 wrote:

var url = "http:// www. contoso.com/"; var request = WebRequest.Create (url);

Which is essentially what it was. But url is a string. I don't see the value in typing var instead of string.

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[Mycroft Holmes]

I use c# and almost never use var, and the content changing comment was a response to some of the previous posts.

Never underestimate the power of human stupidity - RAH I'm old. I know stuff - JSOP

[Fabio Franco]

C# 9.0 will have it: [Welcome to C# 9.0 | .NET Blog](https://devblogs.microsoft.com/dotnet/welcome-to-c-9-0/#target-typed-new-expressions)

To alcohol! The cause of, and solution to, all of life's problems - Homer Simpson ---- Our heads are round so our thoughts can change direction - Francis Picabia

[Fabio Franco]

The problem is that it sometimes becomes a style guideline in teams. I have seen that happening before, which is just stupid to me. "Oh, but you can just hover over it and you will see". This mindset can be a real nightmare on code reviews. I hate the laziness that motivated most var uses I have seen. People don't even know why var was created (to support anonymous types). There are though, as some people have already mentioned, some situations where var makes the code cleaner. But I actually never seen that kind of diligence, so wherever I could I abolished the used of var for non anonymous types. To make matters worse, stupid resharper (that some people like to use) has the default setting that everything should be var. So it pretty much converts the new-comers to the var mindset from the start.

To alcohol! The cause of, and solution to, all of life's problems - Homer Simpson ---- Our heads are round so our thoughts can change direction - Francis Picabia

[zezba9000]

For primitive types I like to say what they're BUT var should be used for most other types. For example

var myGeneric = new List>>();

VS

List>> myGeneric = new List>>();

Both are the same but one much easier to read.

[David On Life]

Dictionary> complicatedDictionary = new ();

Is on the planned list for C# 9.0.

[KateAshman]

In my experience, the need to use var arises from wanting to hide the sometimes lengthy names of collection iterators in foreach declarations. Especially when Linq is used to get the collection, the declaration can become messy. But you now how it goes: first it's to shorten lengthy iterator names, then lengthy class names, then pretty much everywhere because it looks more consistent for some people. I can support the use in foreach declarations, but everywhere else it's more of an annoyance. I never understood the desire to hide stuff like this. It's like an unspoken commitment to never refactor whatever is hidden. On a related note: Regions. Why?

[JohaViss61]

I really like the short notation. When I need to know what type the variable is, I hover the mouse cursor over it and it will show the actual type. And so long as I am not paid by the character, I will use the shortest notation I can use.:cool:

[BDieser]

Resharper encourages var use for whatever reason. However, it does show what the actual type is.

[User 14060113]

There is no advantage. If you just write a scribble, then always using var is Ok. But if you write production-level code, var is sloppy style and thus an absolute no-go. Before IntelliSense was able to automatically convert the var's in your source code to the correct type, var was even an evidence of a programmer not knowing what type they're using. Only exception: Use var to avoid writing the same type twice in the same line. Bad

List list = new List();

Good

var list = new List();

Because then, when you want to change the type, let's say from List to HashSet, you only have to change it once. IntelliSense also suggests this, at least in VS 2017.