Question

I’m wondering if the following is possible:

The method Regex.Match can receive an enum, so I can specify:

RegexOptions.IgnoreCase
RegexOptions.IgnorePatternWhiteSpace
RegexOptions.Multiline

What if I need to specify more than just one? (eg. I want my regex to be Multiline and I want it to ignore the pattern whitespace).

Could I use | operator like in C/C++?

Answer 1

You need to annotate it with [Flags] attribute and use | operator to combine them.

In the case you mentioned, you can do that because RegexOptions enum is annotated with it.

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More References:

A helpful way to use the FlagsAttribute with enumerations

Example Snippet from above CodeProject article:

Definition:

[FlagsAttribute]
public enum NewsCategory : int 
{
    TopHeadlines =1,
    Sports=2,
    Business=4,
    Financial=8,
    World=16,
    Entertainment=32,
    Technical=64,
    Politics=128,
    Health=256,
    National=512
}

Use:

mon.ContentCategories = NewsCategory.Business | 
                        NewsCategory.Entertainment | 
                        NewsCategory.Politics;