Using "var" for string initialization

Question

If I have a string and I initialize it to string.Empty, then

var mystring=string.Empty;

or

string mystring = string.Empty;

Which of the above two should be better wrt performance or any other considerations?

[var (C# Reference)](http://msdn.microsoft.com/en-us/library/bb383973.aspx) — John Woo, Apr 12 '13 at 06:50
`var` is a *compile*-time construct. By the time the code is running, they've become the same code. So there are no performance considerations. — Damien_The_Unbeliever, Apr 12 '13 at 06:52

score 3 · Accepted Answer · answered Apr 12 '13 at 06:53

var is an implicit type. It aliases any type in the C# programming language. The aliased type is determined by the C# compiler.

The var keyword has equivalent performance. It does not affect runtime behavior.

Your both codes generate same IL code;

IL_0000:  nop
IL_0001:  ldsfld     string [mscorlib]System.String::Empty
IL_0006:  stloc.0
IL_0007:  ret

score 0 · Answer 2 · answered Apr 12 '13 at 06:51

0

They both compile to the same IL code, so there is no performance difference during code execution.

However, the second one is more readable, and I would go that way.

answered Apr 12 '13 at 06:51

MarcinJuraszek

1

Respectfully, my style is to always use `var` when I can. It I fine that we disagree, but to infer that one is better than the other on any basis than personal style is presumptious. – Pieter Geerkens Apr 12 '13 at 06:55
I think using `var` while you're initializing simple types, like `int`, `double` or `string` should be avoided, but as you said I's just an opinion. – MarcinJuraszek Apr 12 '13 at 06:56
1

I'm a huge `var` fan too: I don't want to care about types unless I must, being that the compiler is smart enough to allow me to. – Alex Apr 12 '13 at 06:57
One point: In the case of loop indices the use of `var` over `int` or `long` is explicitly recommended by MSDN guidelines – Pieter Geerkens Apr 12 '13 at 07:00

2 Answers2