Server.MapPath specifies the relative or virtual path to map to a physical directory.
Server.MapPath(".")
1 returns the current physical directory of the file (e.g. aspx) being executed
Server.MapPath("..")
returns the parent directory
Server.MapPath("~")
returns the physical path to the root of the application
Server.MapPath("/")
returns the physical path to the root of the domain name (is not necessarily the same as the root of the application)
An example:
Let's say you pointed a web site application (http://www.example.com/
) to
C:\Inetpub\wwwroot
and installed your shop application (sub web as virtual directory in IIS, marked as application) in
D:\WebApps\shop
For example, if you call Server.MapPath()
in following request:
http://www.example.com/shop/products/GetProduct.aspx?id=2342
then:
Server.MapPath(".")
1 returns D:\WebApps\shop\products
Server.MapPath("..")
returns D:\WebApps\shop
Server.MapPath("~")
returns D:\WebApps\shop
Server.MapPath("/")
returns C:\Inetpub\wwwroot
Server.MapPath("/shop")
returns D:\WebApps\shop
If Path starts with either a forward slash (/
) or backward slash (\
), the MapPath()
returns a path as if Path was a full, virtual path.
If Path doesn't start with a slash, the MapPath()
returns a path relative to the directory of the request being processed.
Note: in C#, @
is the verbatim literal string operator meaning that the string should be used "as is" and not be processed for escape sequences.
Footnotes
Server.MapPath(null)
and Server.MapPath("")
will produce this effect too.
Access modifiers
From docs.microsoft.com:
public
The type or member can be accessed by any other code in the same assembly or another assembly that references it.
private
The type or member can only be accessed by code in the same class or struct.
protected
The type or member can only be accessed by code in the same class or struct, or in a derived class.
private protected
(added in C# 7.2)
The type or member can only be accessed by code in the same class or struct, or in a derived class from the same assembly, but not from another assembly.
internal
The type or member can be accessed by any code in the same assembly, but not from another assembly.
protected internal
The type or member can be accessed by any code in the same assembly, or by any derived class in another assembly.
When no access modifier is set, a default access modifier is used. So there is always some form of access modifier even if it's not set.
The static modifier on a class means that the class cannot be instantiated, and that all of its members are static. A static member has one version regardless of how many instances of its enclosing type are created.
A static class is basically the same as a non-static class, but there is one difference: a static class cannot be externally instantiated. In other words, you cannot use the new keyword to create a variable of the class type. Because there is no instance variable, you access the members of a static class by using the class name itself.
However, there is a such thing as a static constructor. Any class can have one of these, including static classes. They cannot be called directly & cannot have parameters (other than any type parameters on the class itself). A static constructor is called automatically to initialize the class before the first instance is created or any static members are referenced. Looks like this:
static class Foo()
{
static Foo()
{
Bar = "fubar";
}
public static string Bar { get; set; }
}
Static classes are often used as services, you can use them like so:
MyStaticClass.ServiceMethod(...);
Best Solution
A Url is path + querystring, and the linked article only talks about limiting the path. Therefore, if you're using asp.net, don't exceed a path of 260 characters. Less than 260 will always work, and asp.net has no troubles with long querystrings.
Typically the issue is with the browser. Long ago I did tests and recall that many browsers support 4k url's, except for IE which limits it to 2083, so for all practical purposes, limit it to 2083. I don't know if IE7 and 8 have the limitation, but if you're going to broad compatibility, you need to go for the lowest common denominator.