In C# 5 and earlier, to give auto implemented properties an initial value, you have to do it in a constructor.
Since C# 6.0, you can specify initial value in-line. The syntax is:
public int X { get; set; } = x; // C# 6 or higher
DefaultValueAttribute
is intended to be used by the VS designer (or any other consumer) to specify a default value, not an initial value. (Even if in designed object, initial value is the default value).
At compile time DefaultValueAttribute
will not impact the generated IL and it will not be read to initialize the property to that value (see DefaultValue attribute is not working with my Auto Property).
Example of attributes that impact the IL are ThreadStaticAttribute
, CallerMemberNameAttribute
, ...
There is actually a (subtle) difference between the two. Imagine you have the following code in File1.cs:
// File1.cs
using System;
namespace Outer.Inner
{
class Foo
{
static void Bar()
{
double d = Math.PI;
}
}
}
Now imagine that someone adds another file (File2.cs) to the project that looks like this:
// File2.cs
namespace Outer
{
class Math
{
}
}
The compiler searches Outer
before looking at those using
directives outside the namespace, so it finds Outer.Math
instead of System.Math
. Unfortunately (or perhaps fortunately?), Outer.Math
has no PI
member, so File1 is now broken.
This changes if you put the using
inside your namespace declaration, as follows:
// File1b.cs
namespace Outer.Inner
{
using System;
class Foo
{
static void Bar()
{
double d = Math.PI;
}
}
}
Now the compiler searches System
before searching Outer
, finds System.Math
, and all is well.
Some would argue that Math
might be a bad name for a user-defined class, since there's already one in System
; the point here is just that there is a difference, and it affects the maintainability of your code.
It's also interesting to note what happens if Foo
is in namespace Outer
, rather than Outer.Inner
. In that case, adding Outer.Math
in File2 breaks File1 regardless of where the using
goes. This implies that the compiler searches the innermost enclosing namespace before it looks at any using
directive.
Best Answer
Use OpenFileDialog.SafeFileName
OpenFileDialog.SafeFileName
Gets the file name and extension for the file selected in the dialog box. The file name does not include the path.