What is the difference between String and string in C#?

c# .net string types alias
Lance Fisher picture Lance Fisher · Aug 10, 2008 · Viewed 1.1M times · Source

Example (note the case):

string s = "Hello world!";
String s = "Hello world!";

What are the guidelines for the use of each? And what are the differences?

Answer

Derek Park picture Derek Park · Aug 10, 2008

string is an alias in C# for System.String.
So technically, there is no difference. It's like int vs. System.Int32.

As far as guidelines, it's generally recommended to use string any time you're referring to an object.

e.g. 

string place = "world";

Likewise, I think it's generally recommended to use String if you need to refer specifically to the class.

e.g.

string greet = String.Format("Hello {0}!", place);

This is the style that Microsoft tends to use in their examples.

It appears that the guidance in this area may have changed, as StyleCop now enforces the use of the C# specific aliases.

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