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c#string.net-3.5string-interpolation

Is it possible to include a C# variable in a string variable without using a concatenator?


Does .NET 3.5 C# allow us to include a variable within a string variable without having to use the + concatenator (or string.Format(), for that matter).

For example (In the pseudo, I'm using a $ symbol to specify the variable):

DateTime d = DateTime.Now;
string s = "The date is $d";
Console.WriteLine(s);

Output:

The date is 4/12/2011 11:56:39 AM

Edit

Due to the handful of responses that suggested string.Format(), I can only assume that my original post wasn't clear when I mentioned "...(or string.Format(), for that matter)". To be clear, I'm well aware of the string.Format() method. However, in my specific project that I'm working on, string.Format() doesn't help me (it's actually worse than the + concatenator).

Also, I'm inferring that most/all of you are wondering what the motive behind my question is (I suppose I'd feel the same way if I read my question as is).

If you are one of the curious, here's the short of it:

I'm creating a web app running on a Windows CE device. Due to how the web server works, I create the entire web page content (css, js, html, etc) within a string variable. For example, my .cs managed code might have something like this:

string GetPageData()
    {
    string title = "Hello";
    DateTime date = DateTime.Now;

    string html = @"
    <!DOCTYPE html PUBLIC ...>
    <html>
    <head>
        <title>$title</title>
    </head>
    <body>
    <div>Hello StackO</div>
    <div>The date is $date</div>
    </body>
    </html>
    ";

}

As you can see, having the ability to specify a variable without the need to concatenate, makes things a bit easier - especially when the content increases in size.


Solution

  • Almost, with a small extension method.

    static class StringExtensions
    {
        public static string PHPIt<T>(this string s, T values, string prefix = "$")
        {
            var sb = new StringBuilder(s);
            foreach(var p in typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance))
            {
                sb = sb.Replace(prefix + p.Name, p.GetValue(values, null).ToString());
            }
            return sb.ToString();
        }
    }
    

    And now we can write:

    string foo = "Bar";
    int cool = 2;
    
    var result = "This is a string $foo with $cool variables"
                 .PHPIt(new { 
                        foo, 
                        cool 
                    });
    
    //result == "This is a string Bar with 2 variables"