"This expression causes side effects and will not be evaluated". How to suppress?

I'm getting thi开发者_如何学运维s message in watch box.

Actually, my expression doesn't have any side effect, and I need to re-evaluate it automatically each time. How can I achieve that?

You can append ,ac to the watch expression to have it automatically refresh the value

x.ToString(),ac

See http://msdn.microsoft.com/en-us/library/e514eeby.aspx for more information and other format specifiers.

thanks to Scott Visual Studio: Make debugger aware that a function doesn't cause "side effects"