Suggestion for SubstringOrDefault To Avoid Out Of Range Error with Substring Command and Having to First Check Length Is Longer

[robinwilson16]

When transferring data from one system to another or inserting user defined data you may not know how long the resulting string is but if you are inserting into a field that is 100 chars then if <= the max then you want to add it all but if over you may want to insert up to the limit.

For this reason having SubstringOrDefault would be handy and would save you having to only call the function if the string is at least that length to avoid an out of bounds error message.

Here is a definition of what it could look like:

public static class StringFunctions
{
    public static string? SubstringOrDefault(this string? value, int? startIndex)
    {
        string? result;
        if (startIndex == null)
            result = value;
        else if (value?.Length < startIndex)
            result = value;
        else
            result = value?.Substring((int)startIndex);

        return result;
    }

    public static string? SubstringOrDefault(this string? value, int? startIndex, int? length)
    {
        string? result;
        if (startIndex == null)
            result = null;
        else if (value?.Length < startIndex)
            result = value;
        else if (length == null)
            result = value?.Substring((int)startIndex);

        if (value?.Length > length - startIndex)
            result = value?.Substring((int)startIndex!, (int)length!);
        else
            result = value;

        return result;
    }
}

[elgonzo]

Word for word an exact duplicate of #110794

[robinwilson16]

Yes it is but I was asked to post it in the runtime repository so that is what I did.
I still think it may be worth considering to be added and the naming fits with other XOrDefault methods that avoid runtime errors.
If not in the right place perhaps someone with the power could move it?

[robinwilson16]

Ok looks like someone did move it so this probably needs to be closed. I hadn't realised sorry.

[robinwilson16]

Closing this duplicate thread. All discussions should go to #110794