C# – Getting the handle of window in C#

cwindowswpf

I have the following class declared:

public partial class MainWindow : Window

And I need to get the actual handle of the window once the window has one.
How can I do that and where should I put the query function.

What I tried so far was:

IntPtr hwnd = new WindowInteropHelper(this).Handle;

But the handle I get back is 0, which might be because it was planted in OnInitialized – maybe the window is not ready yet at that stage.
And, yes – it is connected via WPF, thank you for pointing it out!

Thanks

Best Answer

In the OnInitialized method the handle has not yet been created. But you are on the right track. If you put your call in the Loaded event the handle will have been created and it should return the correct handle.

This is the style that Microsoft tends to use in their examples.

It appears that the guidance in this area may have changed, as StyleCop now enforces the use of the C# specific aliases.

C# – Should ‘using’ directives be inside or outside the namespace

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

Related Solutions

C# – the difference between String and string in C#

This is the style that Microsoft tends to use in their examples.

C# – Should ‘using’ directives be inside or outside the namespace

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