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Summary

Retrieves a handle for each module in the specified process.

C# Signature:

[DllImport("psapi.dll", SetLastError = true)]
public static extern bool EnumProcessModules(IntPtr hProcess,
[MarshalAs(UnmanagedType.LPArray, ArraySubType = UnmanagedType.U4)] [In][Out] uint[] lphModule, uint cb, [MarshalAs(UnmanagedType.U4)] out uint lpcbNeeded);

VB.NET Signature:

<DllImport("psapi.dll", SetLastError:=True)> _
Public Shared Function EnumProcessModules(ByVal hProcess As IntPtr, <MarshalAs(UnmanagedType.LPArray, ArraySubType := UnmanagedType.U4)> <[In]()> <Out()> ByVal lphModule As UInteger(), ByVal cb As UInteger, <MarshalAs(UnmanagedType.U4)> ByRef lpcbNeeded As UInteger) As Boolean
End Function

User-Defined Types:

None.

Alternative Managed API:

System.Diagnostics.Process.Modules

Notes:

I found that the C# signature above did not work for me.  Instead I am using the following signature:
c[DllImport("psapi.dll", CallingConvention=CallingConvention.StdCall, SetLastError = true)]
public static extern int EnumProcessModules(IntPtr hProcess, [Out] IntPtr lphModule, uint cb, out uint lpcbNeeded);

Tips & Tricks:

Please add some!

Sample Code:

Used in conjuction with GetModuleFileNameEx:

        Process[] pc = Process.GetProcessesByName("communicator");

        foreach (Process p in pc)
        {
        // Setting up the variable for the second argument for EnumProcessModules
        IntPtr[] hMods = new IntPtr[1024];

        GCHandle gch = GCHandle.Alloc(hMods, GCHandleType.Pinned); // Don't forget to free this later
        IntPtr pModules = gch.AddrOfPinnedObject();

        // Setting up the rest of the parameters for EnumProcessModules
        uint uiSize = (uint)(Marshal.SizeOf(typeof(IntPtr)) * (hMods.Length));
        uint cbNeeded = 0;

        if (EnumProcessModules(p.Handle, pModules, uiSize, out cbNeeded) == 1)
        {
            Int32 uiTotalNumberofModules = (Int32)(cbNeeded / (Marshal.SizeOf(typeof(IntPtr))));

            for (int i = 0; i < (int)uiTotalNumberofModules; i++)
            {
            StringBuilder strbld = new StringBuilder(1024);

            GetModuleFileNameEx(p.Handle, hMods[i], strbld, (uint)(strbld.Capacity));
            Console.WriteLine("File Path: " + strbld.ToString());
            Console.WriteLine();
            }
            Console.WriteLine("Number of Modules: " + uiTotalNumberofModules);
            Console.WriteLine();
        }

        // Must free the GCHandle object
        gch.Free();
        }

Documentation

EnumProcessModules on MSDN