comp = StringComparison.OrdinalIgnoreCase Console.WriteLine(" {0:G}: {1}", comp, s.Contains(sub1, comp)) That seems like the way. However, I tried and it doesn't work. It seems that the only altenative of s.Contains take char() as first argument. If I want to insert string as first argument then I cannot have second argument as StringComparison.OrdinalIgnoreCase.
I got the snippet from https://msdn.microsoft.com/en-us/library/dy85x1sa(v=vs.110).aspx
You can use IndexOf function.
Console.WriteLine(s.IndexOf(sub1, 0, StringComparison. OrdinalIgnoreCase) > -1) Above snippet prints true or false depending on whether s contains sub1.
Alternatively, if you want to use contains, you can use ToUpper or ToLower as shown below...
Console.WriteLine(" {0:G}: {1}", comp, s.ToUpper().Contains(sub1.ToUpper())) The link you gave in question shows you how to create a custom extension to string. He also gave the code you have to use to create that custom extension and that method uses IndexOf internally if you had observed.
Try this:
s.ToLowerInvariant().Contains(sub1.ToLowerInvariant()) The link you pointed to in your question defines the follow extension method:
Imports System.Runtime.CompilerServices Module StringExtensions <Extension()> Public Function Contains(str As String, substring As String, comp As StringComparison) As Boolean If substring Is Nothing Then Throw New ArgumentNullException("substring", "substring cannot be null.") Else If Not [Enum].IsDefined(GetType(StringComparison), comp) Throw New ArgumentException("comp is not a member of StringComparison", "comp") End If Return str.IndexOf(substring, comp) >= 0 End Function End Module Unless you implement this your call to s.Contains(sub1, comp) won't work.
IndexOf already throws the same exceptions when the arguments are bad. See msdn.microsoft.com/en-us/library/ms224425%28v=vs.110%29.aspx