What is the equivalent command to PHP's include() in C# ?
For example, PHP's include is used as so : include("ex.php");
Can I do the same in C#?
If you mean in ASP.Net using C# you can create a user control (.ascx) and add it in your .aspx page.
If you are doing MVC you can create a partial view.
The closest thing I can think of would be after creating an ascx user control named "MyUserControl"
in your page_load or pre_render :
MyUserControl cont = new MyUserControl();
this.Controls.Add(cont);
There is no such thing in C#. It's not a scripting language, so including a block of script wouldn't make sense.
What are you trying to accomplish? There are ways to do similar things in C#.
There is no direct equivalent. You use references to "link" with other CLR assemblies (access their type information), and the using directive to import namespaces.
For example, the FontCollection class is in the System.Drawing.dll assembly, and the System.Drawing.Text namespace. So you would add System.Drawing as a reference, and add the line:
using System.Drawing.Text;
I'm not sure, if this is what you want to do. But just for the case, maybe you have a look at:
<%
Response.WriteFile( "YourFile.whatever" )
%>
In addition to previous answers mentioning the using Directive and adding references to assemblies to your project (or at command line when compiling) there is a way to load other compiled .NET assemblies at runtime.
Assembly.Load will load an assembly (compiled c# file/.dll) into memory, allowing you to find and use types within that assembly. This can be used when building a plugin architecture. You publish an assembly with an interface for a plugin contract. Plugin makers can link to that that assembly and implement your interface. Your application can then load plugin assemblies, check for any types implementing your plugin interface and load and use those types into your application.
The only thing comparable in C# is using, which imports namespaces defined in assemblies referenced from the project. You cannot "include" a file in the sense that you dump the content right into your code.
For example, if your project references the System.Xml assembly, then the following code would allow you to access all of the classes in that namespace without fully qualifying their names:
using System.Xml;
This will let you use the type System.Xml.XmlDocument, for example, by specifying it as XmlDocument instead of its full type name System.Xml.XmlDocument.
There is no such thing in C#.
You're going to want to create an instance of a C# class and use that to invoke methods/attributes from other 'packages' (C# classes).
You can also use a using direction to be able to references assemblies from other projects.
Using is vaguely similar. It references another class that can then be used from that file, but it doesn't include the contents of that file directly inline.
using system;
(right at the beginning of a file)
Use this for c#
#RenderPage("header.cshtml")
This is taken from here:
http://www.w3schools.com/aspnet/showfile_c.asp?filename=try_webpages_cs_002
Although I know this post is old, but people stubming to this post can refer to it.
Well, here is what I did ... not sure if this is the right way, but it works...
In the .ascx File, specify a div as container to received the contents of included file.
<div id="containerForSomeMarkup" runat="server"></div>
In the .ascx.cs file, initialise this in the onInit() method or other methods as required...
containerForSomeMarkup.InnerHtml = File.ReadAllText("Full path of file to be included");
Coming from PHP world, for me, this approach helps keep the markup organized and intelligble...
The using keyword is what you're looking for.
Related
Sorry if this question was asked already.
I started studying C# and noticed that C# doesn't automatically import nested namespaces.
I don't understand:
using System;
should automatically import all classes contained in the System namespace right?
So there should be no need for me to write
using System.Windows.Form;
I would understand if using Windows.Form even worked. But the compiler could not resolve it! What is the point of the using System; before it then?
So why does using System; not import System.Windows automatically as well as System.Windows.Forms - sorry if the word import is wrong here.. maybe move to global namespace is the right terminology.
C# is not Java.
A using directive is used so you don't have to type in the fully qualified name of a type. It also helps with disambiguating type names (using aliases for instance).
In the case of Console, for example, you don't need to type System.Console.
It is important to understand the difference between a namespace and an assembly - a namespace is a logical grouping of types. An assembly is a physical grouping of types. Namespaces can span assemblies.
When you reference an assembly (this is more like importing a package in Java), you gain access to all of the public types in it. In order to use a type you need to uniquely identify it. This is done through the namespace - the using directive simply means you don't have to type the fully qualified name of the type.
The using directive has two uses:
To allow the use of types in a namespace so that you do not have to
qualify the use of a type in that namespace:
using System.Text;
To create an alias for a namespace or a type. This
is called a using alias directive.
using Project = PC.MyCompany.Project;
http://msdn.microsoft.com/en-us/library/sf0df423.aspx
However, you have to note that System and System.Windows.Form are not connected through name itself in anyway. If you import (using) System that means you will use the System assembly types in this class. Actual reference you specify in references section in Visual Studio project which you can really use (even without using statement, as this is just a shortcut for types).
C# doesn't import nested namespaces and this is by design.
Namespace scope lets you organize code and gives you a way to create
globally unique types.
Nested namespaces are used to group related functionality, but use parts of it on-demand.
I guess you wouldn't want to have all the types from such a big namespace like System if the only thing you need is System.Windows.
So probably the question is why C# doesn't have something like using System.*; like java does. I don't know the answer, but I guess this is because of KISS principle. It's something like using
select *
you will never know what types you will add and how they will affect existing code.
Even in Java you'd have to explicitly write
import System.*;
Much of the time you don't want all of the nested namespaces. These would simply clutter IntelliSense.
The "using" syntax allows you shorthand access to namespaces that are already listed as References in the project settings. If the namespace is listed as a reference you already have access to it by it's full name without the "using" directive. Just saves keystrokes.
"Using" a given namespace means that you will get access to all definitions implemented directly in it, not that it will recursively look up the embedded namespaces; doing otherwise would defeat the purpose of the "Using" statement.
Namespaces exist to avoid class name ambiguity. The "Using" statement is here to avoid the use of fully qualified types nested in namespaces, when you know no (or little) ambiguity may occur.
No, this is not how it works.
And I will give a good argument against what you said: intellisnse would go crazy and finding the what you want would be hell.
You do have access to everything on every namespace available (with dots), the using keyword simplifies this because you don't have to specify from which namespace a class or struct is "coming from" (I mean, defined).
High-level question here:
I have spent a lot of time today educating myself on basic high-level concepts such as APIs, static and dynamic libraries, DLLs and marshaling in C#. Gaining all of this knowledge led me to what seems like a pretty basic question, and probably demonstrates a hole in my understanding of these concepts:
What I know:
DLLs may contain classes which in turn contains various class-members such as methods and fields, several of which I might want to utilize in my program
In C# we use the keyword "using" at the top of the code, to define a namespace we
want to include in our program
What I do not get:
I was under the impression that the actual methods were defined in the DLLs. How does my program find the actual functions that are defined in the DLLs, when all i give them is a namespace? It seems more intuitive to me to have "using XYZ.dll" at top, rather than "using XYZ_namespace".
Thanks a lot for helping me fill in the gaps here.
EDIT: Modified post to be specific to C#.
EDIT 2: For other people that wonder how their C# application actually gets a hold of the types made available through "using namespaceX", this is a good resource (in addition to the helpful posts below): http://broadcast.oreilly.com/2010/07/understanding-c-namespaces-and.html.
Basically the type you would like to use resides in libraries and you have to set Visual Studio to reference these libraries in order to make it possible to "use" its namespace in your code.
DLLs contain many routines / methods we might want to use in our
programs
Partially correct. .Net DLLs contain Classes, and these classes contain Members (Fields, Constants, Methods, Properties, Events, Operators, Indexers).
.Net is strictly OOP, and it does not allow code "floating in limbo". Everything is defined inside classes.
Classes are organized in Namespaces just to keep a naming separation and organization. Think of namespaces as "folders" that contain one or more classes, and that might be defined in one or more assemblies (DLLs).
For example, Classes inside the System namespace are defined in 2 assemblies (DLLs): mscorlib.dll and System.dll.
At the same time, these 2 assemblies contain many different namespaces, so you can think the Assembly to Namespace relation as a Many-to-Many.
When you put a using directive at the beginning of a C# code file, you're telling the compiler "I want to use classes defined in this Namespace, no matter what assembly they come from". You will be able to use all classes defined in such namespace, inside all assemblies Referenced from within the current project.
In C#, DLLs (aka assemblies) contain classes (and other types). These types typically have long full names, like System.Collections.Generic.List<T>. These types can contain methods.
In your References area, you have references to assemblies (this is part of your .csproj file). In a .cs file, you don't need to include any using to reference this DLL, because it's already referenced in your .csproj file.
If you include a line like using System.Collections.Generic;, that tells the C# compiler to look for System.Collections.Generic.List<T> when you type List<T>. You don't need to do it that way, however: you can simply type System.Collections.Generic.List<T>.
I was under the impression that the actual methods were defined in the
DLLs. How does my program find the actual functions that are defined
in the DLLs, when all i give them is a namespace?
The process of finding the correct code occurs through static or dynamic binding and also assembly binding. When you compile the code static binding will tell you if you wrote bad code or forgot to add a reference:
ClassInADifferentAssembly.M(); //Generally this will static bind and
cause a compiler error if you forgot to include a reference to
DifferentAssembly
Unless you are dealing with dynamic or reflection then you have static binding. Assembly binding is a different process. The overall process is complex, but basically assemblies are discovered in the the GAC, current location or you can even handle an event yourself, AppDomain.AssemblyLoad.
So when you add a using statement then static binding can successfully find the correct code in the context. However, you can still receive a runtime error if later the assembly fails to bind at runtime.
DLL is short for dynamic link library. And can be a class library containing classes, methods etc that can all be put under different namespaces.
So first you have to add a reference to the DLL into your project. When that is done, you then use a keyword such as "using" to basically shorten the path to reach the methods/classes in that particular namespace.
Example namespaces
Namespace.Something.SomethingMore.Finally.Just.One.More
Namespace.Something.SomethingMore.Finally.Just.One.More2
To reach classes under those namespaces you can do either of the following
using Namespace.Something.SomethingMore.Finally.Just.One.More;
using Namespace.Something.SomethingMore.Finally.Just.One.More2;
// Now you can access classes under those namespaces without typing the whole namespace
// Like in the row below
Class.GetData();
If you did not have the usings, you would still be able to access those classes. But would then have to type
Namespace.Something.SomethingMore.Finally.Just.One.More.Class.GetData();
Namespace.Something.SomethingMore.Finally.Just.One.More2.AnotherClass.GetData();
DLLs have a collection of functions.
You can calls these functions by one of 2 ways:
link with the DLLs export library (a lib file) or do the link in runtime:
Call LoadLibrary()
Call GetProcAddress and provide the name of the function you want. You'll need to cast it to the actual type (function pointer).
Call the function via the new function pointer.
Pretty simple stuff, just read it on MSDN.
C++ namespaces are just a part of the function name.
You can view what functions are exported from a DLL by using a tool called Dependency Walker.
Is there a way that I can add a default using directive to ScriptCS? So when I start ScriptCS I do not need to include the namespace for classes in that namespace.
For example, I may need to interact with the Process class within the System.Diagnostics namespace a lot. If I want to create a new instance of this class, I need to do
var proc = new System.Diagnostics.Process();
I would rather do
var proc = new Process();
I know that I can add the using statement each time I start ScriptCS, but I would like it to always be there.
You can add additional assembly references and using statements into your en and by writing a Script Pack. You can see an example of injecting using statements in the Web API example.
A script pack can do this as Justin mentioned. An alternative option would be to use global modules, example here (https://github.com/scriptcs-contrib/scriptcs-sample-module) however currently they don't support this nicely. If the module had a hook for getting all the services after they were created, you could do this.
I filed this bug (https://github.com/scriptcs/scriptcs/issues/472) to allow addressing this in a much cleaner fashion.
Looks like this can be accomplished by modifying the DefaultNamespaces property of the ScriptExecutor class to include the namespace you want to always have.
You would need to download the source (or fork a new branch in github), modify and compile yourself. You would then put the new ScriptCs.Core assembly in the install folder (C:\Users\USER_NAME\AppData\Roaming\scriptcs). This would replace the existing assembly. If you do this you will lose any changes if you are updating through chocolatey
Is it possible to load a class and create Instance of it from It's .cs file?
I want to open a custom class in a .cs file and create instance of it in my application
thanks
in theory yes - it mainly depends on whether you have all dependencies available...
IF so you can use the built-in CSharpCodeProvider to compile the .cs- file to an assembly (can be purely in-memory if need be) and then use Reflection to create an instance/use a class from that assembly...
Since don't provide much detail I would suggest to checkout these links and come back with detail questions if some arrise:
http://support.microsoft.com/kb/304655/en-us
http://www.codeproject.com/KB/cs/codecompilation.aspx
http://www.digitalcoding.com/Code-Snippets/C-Sharp/C-Code-Snippet-Compile-C-or-VB-source-code-run-time.html
http://www.c-sharpcorner.com/UploadFile/mgold/CodeDomCalculator08082005003253AM/CodeDomCalculator.aspx
http://www.csharp-examples.net/reflection-examples/
http://csharp.net-tutorials.com/reflection/introduction/
http://www.codeproject.com/KB/cs/C__Reflection_Tutorial.aspx
http://www.dotnetperls.com/reflection-field
C# Reflection: How to get class reference from string?
http://msdn.microsoft.com/en-us/library/system.reflection.assembly.aspx
http://msdn.microsoft.com/en-us/library/system.type.aspx
You can use Microsoft.CSharp.CSharpCodeProvider and System.CodeDom to execute code at runtime, there is an article about this code project here and here
Normally we all do use using System.Linq; and using System.Data.Linq; for example on the code-behind and expect we can reach the members of these namespaces from Source Code like <%= Something.First()%> but when I wrote it, asp.net said it couldn't find First() in the context and I had to add <%# Import Namespace="System.Linq" which looked very weird to me but it worked out. Since they are targeting at the same class why they both need separate namespace importing.
Code-behind :
using System;
using System.Data.Linq;
using System.Linq;
using System.Text
namespace Something
{
class Items : System.Web.UI
{
//...
}
}
but also I need to add the same Linq namespace on the Html Source part
<%#Import Namespace="System.Linq"%>
Do I know something wrong or this is some kind of bug in asp.net. I thought when the page is compiling, asp.net combines these two classes and converts html source code into cs class and indicates the control in Control c= new Control(); hierarchy.
Thanks in advance.
P.s : I am trying to reach for example First() in Items.aspx and everything I mentioned about an asp.net page which is Items.aspx
You must specify your namespaces in both places. It's normal behavior. That's needed by the compiler in order to pre-compile the aspx page and the code-behind page separately, before merging them into one class and doing the actual compilation.
By default, a few common namespaces are already included in the aspx page, so you don't need to import them. But in your case you need to import Linq.
EDIT: And as Joel Coehoorn said, you can add to that list of default namespaces in Web.config, should you not want to manually add them in the aspx pages.
Check your web.config file for a namespaces section and make sure System.Linq is listed there.
Documentation:
http://msdn.microsoft.com/en-us/library/ms164642.aspx
I would not use First in markup, if you still want to do it , make a wrapper in your code behind , like SomeMethod or SomeProperty and access it from markup as <%=SomeProperty %>
First is not a method on the class, but an extension method defined in the System.Linq namespace. Even though you may also use this extension method within the code behind, this doesn't mean that the ASP.NET compiler can find the extension method without a hint - hence the <%# Imports ... %> directive.
Note that the ASP.NET compilation (i.e. of the aspx) is separate from the compilation of the code behind. The latter runs when you build the project; the former runs when you either access the page for the first time, or pre-compile it using "Publish..." or a web deployment project. Hence each compiler needs to be told where to find this extension method if you use it in both places.