在LINQ语句中添加条件

Question

I've a C# statement as follows:

var errors =  errorList.Select((e, i) => string.Format("Error occured #{0}: {1} (Error code = {2}).", i + 1, e.Message, e.ErrorCode)).ToArray();

I need to display "Error occured" when e.ErrorCode is 'Error' and "Warning occured" when e.ErrorCode is 'Warning'. How do I add this condition to the above statement please?

Thanks.

Answer 1

你能不能这样做：

errorList.Select((e, i) => string.Format("{2} Occured #{0}: {1} (Error code = {2}).", i + 1, e.Message, e.ErrorCode)).ToArray();

Answer 2

I would probably just wrap the slightly more complex logic into another method like so..

        private string GetErrorCodeLogLabel(ErrorCode code)
        {
            if(code == ErrorCode.Error /* || .. other errors*/)
                return "Error";
            else if (code == ErrorCode.Warning /* || .. other warnings*/)
                return "Warning";

            throw new NotImplementedException(code);
        }

        var errors = errorList.
            Select((e, i) => string.Format("{0} occured #{1}: {2} (Error code = {3}).", GetErrorCodeLogLabel(e.ErrorCode), i + 1, e.Message, e.ErrorCode)).
            ToArray();

Answer 3

You can use inline if: (you may modify the conditions)

    var errors = errorList.Select((e, i) => string.Format("{0} occured #{1}: {2} (Error code = {3}).", 
                 e.ErrorCode == ErrorCode.Error ? "Error" : "Warning",
                 i + 1, 
                 e.Message, 
                 e.ErrorCode)).ToArray();