Cannot convert from method group to System.Func

Question

I'm playing a bit with the .Net 4.0 Task class to download the google webpage in background using a thread. The problem is that if my function has 1 or more parameters, the application won't compile (idk how to pass that parameter). So I wonder how can I pass the function's parameter in the DoWork() method.

This works:

    public Task<String> DoWork() {
        //create task, of which runs our work of a thread pool thread
        return Task.Factory.StartNew<String>(this.DownloadString);

    }


    private String DownloadString()
    {
        using (var wc = new WebClient())
            return wc.DownloadString("http://www.google.com");
    }

This doesn't:

    public Task<String> DoWork() {
        //create task, of which runs our work of a thread pool thread
        return Task.Factory.StartNew<String>(this.DownloadString);

    }


    private String DownloadString(String uri)
    {
        using (var wc = new WebClient())
            return wc.DownloadString(uri);
    }

The error is:

cannot convert from 'method group' to 'System.Func<string>'

Thank you in advance!

How is your second snippet supposed to know what to download? Where are you passing the `uri` parameter? — Blorgbeard, Mar 31 '15 at 19:17
Well, that's what the compiler error is.. your `DownloadString` is not a `Func`, it's a `Func`. Task.StartNew is expecting the former, not the latter. — Blorgbeard, Mar 31 '15 at 19:21

score 3 · Answer 1 · answered Mar 31 '15 at 19:21

return Task.Factory.StartNew(() => DownloadString("https://www.google.com"));

or

return Task.Factory.StartNew(() =>
            {
                using (var wc = new WebClient())
                    return wc.DownloadString("https://www.google.com");
            });

EZI · Accepted Answer · 2015-03-31T19:21:53.180

2

return Task.Factory.StartNew(() => this.DownloadString("http://...."));

edited Mar 31 '15 at 19:21

answered Mar 31 '15 at 19:19

EZI

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Delegate 'System.Func' does not take 1 arguments – Daniel Pascal Mar 31 '15 at 19:21
it works, thank you. It's kinda obvious, so simple. Since you answered first, I'll accept yours. – Daniel Pascal Mar 31 '15 at 19:31

Cannot convert from method group to System.Func

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