c# - Regex pattern for checking if a string starts with a certain substring?

Question

What's the regular expression to check if a string starts with "mailto" or "ftp" or "joe" or...

Now I am using C# and code like this in a big if with many ors:

String.StartsWith("mailto:")
String.StartsWith("ftp")

It looks like a regex would be better for this. Or is there a C# way I am missing here?

Answer 1

You could use:

^(mailto|ftp|joe)

But to be honest, StartsWith is perfectly fine to here. You could rewrite it as follows:

string[] prefixes = { "http", "mailto", "joe" };
string s = "joe:bloggs";
bool result = prefixes.Any(prefix => s.StartsWith(prefix));

You could also look at the System.Uri class if you are parsing URIs.