CODEWITHSUNDEEP
c#bitmaskintptr
dotNET
dotNET

Reputation: 35450

Bit masking an IntPtr

How do I use Binary-AND to check if a particular bit is set for an IntPtr object?

I'm calling GetWindowLongPtr32() API to get window style for a window. This function happens to return an IntPtr. I have defined all the flag constants in my program. Now suppose if I want to check whether a particular flag (say WS_VISIBLE) is set, I need to Binary-AND it with my constant, but my constant is of int type, so I cannot do that directly. Try to call ToInt32() and ToInt64() both result in (ArgumentOutOfRangeException) exception. What's my way out?

Upvotes: 2

Views: 1508

Answers (2)

Dustin Kingen
Dustin Kingen

Reputation: 21265

How do I pinvoke to GetWindowLongPtr and SetWindowLongPtr on 32-bit platforms?

public static IntPtr GetWindowLong(HandleRef hWnd, int nIndex)
{
    if (IntPtr.Size == 4)
    {
        return GetWindowLong32(hWnd, nIndex);
    }
    return GetWindowLongPtr64(hWnd, nIndex);
}


[DllImport("user32.dll", EntryPoint="GetWindowLong", CharSet=CharSet.Auto)]
private static extern IntPtr GetWindowLong32(HandleRef hWnd, int nIndex);

[DllImport("user32.dll", EntryPoint="GetWindowLongPtr", CharSet=CharSet.Auto)]
private static extern IntPtr GetWindowLongPtr64(HandleRef hWnd, int nIndex);

GetWindowLong(int hWnd, GWL_STYLE) return weird numbers in c#

You can implicit cast IntPtr to int to get the result.

var result = (int)GetWindowLong(theprocess.MainWindowHandle, GWL_STYLE);
bool isVisible = ((result & WS_VISIBLE) != 0);

Upvotes: -1

Peter Ritchie
Peter Ritchie

Reputation: 35869

Just convert IntPtr to an int (it has a conversion operator) and use logical bit operators to test bits. 

const int WS_VISIBLE = 0x10000000;
int n = (int)myIntPtr;
if((n & WS_VISIBLE) == WS_VISIBLE) 
    DoSomethingWhenVisible()`

Upvotes: 2

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