c#-3.0

问题 Is it possible to implement a ! (not) using expression trees. I'm interested in creating a C# eval class which will parse and evaluate logical expressions which contain true, false, ||, && and !. I know that && and || are currently supported by .NET 4 expression trees, but I was wondering if their is a way to implement summat like !(x && y) || z where z=false, y=true and z=false. Currently I'm using a standard stack based tokenizer, parser, evaluator to evaluate these types of expression but

问题 Is it possible to implement a ! (not) using expression trees. I'm interested in creating a C# eval class which will parse and evaluate logical expressions which contain true, false, ||, && and !. I know that && and || are currently supported by .NET 4 expression trees, but I was wondering if their is a way to implement summat like !(x && y) || z where z=false, y=true and z=false. Currently I'm using a standard stack based tokenizer, parser, evaluator to evaluate these types of expression but

问题 As the title describes, I have a set of objects - call them Allocations - which contain a description & a number. All numbers in the set add up to 100%, but for display purpose I sometimes round to a whole percent. In some edge cases, having rounded the numbers I end up with 99%. Example: Description | Actual | Rounded =============================== Allocation A | 65.23% | 65% Allocation B | 25.40% | 25% Allocation C | 7.95% | 8% Allocation D | 1.42% | 1% ===============================

问题 "Fluent interfaces" is a fairly hot topic these days. C# 3.0 has some nice features (particularly extension methods) that help you make them. FYI, a fluent API means that each method call returns something useful, often the same object you called the method on, so you can keep chaining things. Martin Fowler discusses it with a Java example here. The concept kooks something like this: var myListOfPeople = new List<Person>(); var person = new Person(); person.SetFirstName("Douglas").SetLastName

问题 This question already has answers here : Detect IE version from a WinForms application (5 answers) Closed 6 years ago . I am developing an winform application in .NET framework 3.5, using C#. In the application I need to display the IE version number, installed on the machine on which it runs. How can I do that, can anybody tell me? 回答1: You can read the version from the registry: var ieVersion = Registry.LocalMachine.OpenSubKey(@"Software\Microsoft\Internet Explorer").GetValue("Version");

问题 Why do extension methods require the declaring class to be static? Is it a compiler requirement? 回答1: It's dictated in the language specification, section 10.6.9 of the C# 4 spec: When the first parameter of a method includes the this modifier, that method is said to be an extension method. Extension methods can only be declared in non-generic, non-nested static classes. The first parameter of an extension method can have no modifiers other than this, and the parameter type cannot be a

问题 I have written a winform application in C#. When I run the program for some functionality it required admin permission. After Installation If I set the .exe file to run as admin manually (by clicking right mouse button on .exe file) then my program run perfectly. Now I need user not to set the run as admin property after installation by clicking right mouse button. I need to set this programaticaly somewhere in the code that user no need to bother about this. This specific problem is only

问题 Am saving Webpages from webbrowser control to the directory like below code. Now i want to check all the webpages daily that is modified or not. if it is modified have to update or else leave it. here i tried something in console application. static void Main(string[] args) { Uri myUri = new Uri("http://www.google.com"); // Create a new 'HttpWebRequest' object with the above 'Uri' object. HttpWebRequest myHttpWebRequest = (HttpWebRequest)WebRequest.Create(myUri); // Create a new 'DateTime'

问题 I got the problem in Crystal Report- Error Messsage:Load report failed. how to solve this issue??. 回答1: If your report is running for awhile and then falls over make sure you Dispose it....... if(myReport != null) { myReport .Close(); myReport .Dispose(); } 回答2: You can call show data on report in DataBinding and Navigate methods. protected void CrystalReportViewer1_DataBinding(object sender, EventArgs e) { this.ShowReportData(); } protected void CrystalReportViewer1_Navigate(object source,

问题 I have this strange behavior. Im Loading some entities in a List<> and append to a grid. When double click the grid i take the row cast to the entity and append to a property. I have changed some things in my database and code and now i get this exception while i never wanted to check something on this Entity Reference. Any Ideas? 回答1: This seems to happen to me when I try to access a property that isn't one of the columns on the database table that the entity is derived from. For example,