Avoid exception with C# Substring() method? [duplicate]

Question

Is there another way or a proper way to use SubString()

Here is my sample:

var prefix = "OKA";
Console.WriteLine($"{prefix.Substring(0, 4)}");
// Result: Index and length must refer to a location within the string.Parameter name: length

So to avoid this exception I must write something like this:

var prefix = "OKA";
Console.WriteLine($"{prefix.Substring(0, prefix.Length > 4 ? 4 : prefix.Length)}");
// Result: OKA

This work but become difficult to read when you need to use this trick all the time in your code.

So I there something smart I can use like

var prefix = "OKA";
Console.WriteLine($"{prefix:XX}");
// XX is not working

I also try many alternative and documentation. My conclusion is there is no better solution or I need to write my own formatter but I would like to hear it from you.

Answer 1

you could write an extension method that does the logic for you?

static class SomeHelperClass
{
    public static string Truncate(this string value, int length)
        => (value != null && value.Length > length) ? value.Substring(0, length) : value;
}

and use

Console.WriteLine(prefix.Truncate(4));

?