how to check that a string isn't a keyword or type in c#

I am writing a code generator in which the variable names ar开发者_如何学JAVAe given by the user.

Previous answers have suggested using Regex or CodeDomProvider, the former will tell you if the identifier is valid, but doesn't check keywords, the latter checks keywords, but doesn't appear to check all Types known to the code. How to determine if a string is a valid variable name?

For instance, a user could name a variable List, or Type, but that is not desirable. How would I prevent this?

The easiest way is to add a list of C# keywords to your application. MSDN has a complete list here.

If you really want to get fancy, you could dynamically compile your generated code and check for the specific errors that you're concerned about. In this case, you're specifically looking for error CS1041:

error CS1041: Identifier expected; '**' is a keyword

You'll probably want to ignore any errors regarding unresolved references, undeclared identifiers, etc.

As others have suggested, you could just prepend your identifiers with @, which is fine if you don't want the user to examine the generated code. If it's something they're going to have to maintain, however, I'd avoid that as (in my opinion) it makes the code noisy, just like $ all over the place in PHP or guys that insist on putting this. in front of every freaking field reference.

I'm not sure there is a full API available which will give you what you're looking for. However the end result you seem to be looking for is the generation of code which will not cause conflicts with reserved C# keywords or existing types. If that is the case one approach you can take is to escape all identifiers given by the user with the @ symbol. This allows even reserved keywords in C# to be treated as identifiers.

For example the following is completely valid C# program

class Program
{
    static void Main(string[] args)
    {
        int @byte = 42;
        int @string = @byte;
        int @Program = 0;
    }
}

One option here would be to have your code generator prefix the user-specified name with @. As described in 2.4.2, the @ sign (verbatim identifier):

prefix "@" enables the use of keywords as identifiers, which is useful when interfacing with other programming languages. The character @ is not actually part of the identifier, so the identifier might be seen in other languages as a normal identifier, without the prefix. An identifier with an @ prefix is called a verbatim identifier. Use of the @ prefix for identifiers that are not keywords is permitted, but strongly discouraged as a matter of style.

This would allow you to check for the main keywords, and deny them as needed, but not worry about all of the conflicting type information, etc.

You could just prepend a @ character to the variable - for instance, @private is a valid variable name.