> For the complete documentation index, see [llms.txt](https://pinvokeisalive.gitbook.io/pinvoke/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://pinvokeisalive.gitbook.io/pinvoke/desktopfunctions/kernel32/virtualprotectex.md).

# VirtualProtectEx

### C# Signature:

```cs
[DllImport("kernel32.dll")]
static extern bool VirtualProtectEx(IntPtr hProcess, IntPtr lpAddress,
   UIntPtr dwSize, uint flNewProtect, out uint lpflOldProtect);
```

### VB.Net Signature:

```cs
<DllImport("kernel32", CharSet:=CharSet.Auto, SetLastError:=True)> _
    Public Shared Function VirtualProtectEx(ByVal hProcess As IntPtr, ByVal lpAddress As IntPtr, ByVal dwSize As IntPtr, ByVal flNewProtect As UInteger, ByRef lpflOldProtect As UInteger) As Boolean
    End Function
```

### Boo Signature:

```cs
[DllImport("kernel32.dll")]
def VirtualProtectEx(hProcess as IntPtr, lpAddress as IntPtr, dwSize as UInt32, flNewProtect as UInt32, ref lpflOldProtect as UInt32) as bool:
     pass
```

### VB6 Signature:

```cs
Public Declare Function VirtualProtectEx Lib "kernel32" (ByVal hProcess As Long, ByVal lpAddress As Any, ByVal dwSize As Long, ByVal flNewProtect As Long, ByVal lpflOldProtect As Long) As Long
```

### Tips & Tricks:

```cs
In Essential C# 2.0 by Mark Michaelis, it is mentioned ref is to be used for lpflOldProtect rather than out because the callee can ignore the data passed with ref.
```