条件字符串聚合.net

Question

I have the following code

var definitionMap = definitions.Aggregate("", (current, next) => 
    current +  "[\\W\\s]" + 
    next.Tag.Replace("(", "\\(").Replace(")", "\\)") + "[\\W\\s]" + "|");

This works pretty well except I get a trailing | on the end, I could just remove this manually but is there anyway to stop the aggregate method from putting it there in the first place

Answer 1

You could add it conditionally at the start of each term, ie

(current, next) => (current == "" ? "" : "|") + ...

However, I would also suggest you look at StringBuilder and a foreach loop here instead of Aggregate . Actually, since StringBuilder has a fluent API you can actually use it inside Aggregate - but I don't recommend it. Just because you can use a LINQ extension method doesn't mean it is automatically either clearer or better . In this case, it is neither IMO. In particular, at the moment you are generating a lot of unnecessary intermediate strings.

Answer 2

Why not just go with String.Join and a Select ?

var definitionMap =
    String.Join("|",
        definitions.Select(
            next =>
                "[\\W\\s]"
                + next.Tag.Replace("(", "\\(").Replace(")", "\\)")
                + "[\\W\\s]"));