How can I determine if a NET assembly was built for x86 or x64

Question

I ve got an arbitrary list of  NET assemblies   I need to programmatically check if each DLL was built for x86  as opposed to x64 or Any CPU   Is this possible

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Try to use CorFlagsReader from this project at CodePlex  It has no references to other assemblies and it can be used as is

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You can use the CorFlags CLI tool  for instance  C  Program Files Microsoft SDKs Windows v7 0 Bin CorFlags exe  to determine the status of an assembly  based on its output and opening an assembly as a binary asset you should be able to determine where you need to seek to determine if the 32BIT flag is set to 1  x86  or 0  Any CPU or x64  depending on PE    Option      PE      32BIT ---------- ------- --------- x86         PE32    1 Any CPU     PE32    0 x64         PE32    0   The blog post x64 Development with  NET has some information about corflags   Even better  you can use Module GetPEKind to determine whether an assembly is PortableExecutableKinds value PE32Plus  64-bit   Required32Bit  32-bit and WOW   or ILOnly  any CPU  along with other attributes

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I ve cloned a super handy tool that adds a context menu entry for assemblies in the windows explorer to show all available info   Download here  https   github com tebjan AssemblyInformation releases

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One more way would be to use dumpbin from the Visual Studio tools on DLL and look for the appropriate output  dumpbin exe  HEADERS  lt your dll path gt      FILE HEADER VALUE                  14C machine  x86                     4 number of sections             5885AC36 time date stamp Mon Jan 23 12 39 42 2017                    0 file pointer to symbol table                    0 number of symbols                   E0 size of optional header                 2102 characteristics                        Executable                        32 bit word machine                        DLL   Note  Above o p is for 32bit dll  One more useful option with dumpbin exe is  EXPORTS  It will show you the function exposed by the dll  dumpbin exe  EXPORTS  lt PATH OF THE DLL gt

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Look at System Reflection AssemblyName GetAssemblyName string assemblyFile   You can examine assembly metadata from the returned AssemblyName instance   Using PowerShell     36  C     reflection assemblyname   GetAssemblyName    pwd  Microsoft GLEE dll     fl  Name                    Microsoft GLEE Version                 1 0 0 0 CultureInfo             CodeBase                file    C  projects powershell BuildAnalyzer     EscapedCodeBase         file    C  projects powershell BuildAnalyzer     ProcessorArchitecture   MSIL Flags                   PublicKey HashAlgorithm           SHA1 VersionCompatibility    SameMachine KeyPair                 FullName                Microsoft GLEE  Version 1 0 0 0  Culture neut       Here  ProcessorArchitecture identifies target platform    Amd64  A 64-bit processor based on the x64 architecture  Arm  An ARM processor  IA64  A 64-bit Intel Itanium processor only  MSIL  Neutral with respect to processor and bits-per-word  X86  A 32-bit Intel processor  either native or in the Windows on Windows environment on a 64-bit platform  WOW64   None  An unknown or unspecified combination of processor and bits-per-word    I m using PowerShell in this example to call the method

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Look at System Reflection AssemblyName GetAssemblyName string assemblyFile   You can examine assembly metadata from the returned AssemblyName instance   Using PowerShell     36  C     reflection assemblyname   GetAssemblyName    pwd  Microsoft GLEE dll     fl  Name                    Microsoft GLEE Version                 1 0 0 0 CultureInfo             CodeBase                file    C  projects powershell BuildAnalyzer     EscapedCodeBase         file    C  projects powershell BuildAnalyzer     ProcessorArchitecture   MSIL Flags                   PublicKey HashAlgorithm           SHA1 VersionCompatibility    SameMachine KeyPair                 FullName                Microsoft GLEE  Version 1 0 0 0  Culture neut       Here  ProcessorArchitecture identifies target platform    Amd64  A 64-bit processor based on the x64 architecture  Arm  An ARM processor  IA64  A 64-bit Intel Itanium processor only  MSIL  Neutral with respect to processor and bits-per-word  X86  A 32-bit Intel processor  either native or in the Windows on Windows environment on a 64-bit platform  WOW64   None  An unknown or unspecified combination of processor and bits-per-word    I m using PowerShell in this example to call the method

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How about you just write you own  The core of the PE architecture hasn t been seriously changed since its implementation in Windows 95  Here s a C  example       public static ushort GetPEArchitecture string pFilePath                ushort architecture   0          try                       using  System IO FileStream fStream   new System IO FileStream pFilePath  System IO FileMode Open  System IO FileAccess Read                                 using  System IO BinaryReader bReader   new System IO BinaryReader fStream                                         if  bReader ReadUInt16      23117    check the MZ signature                                               fStream Seek 0x3A  System IO SeekOrigin Current     seek to e lfanew                          fStream Seek bReader ReadUInt32    System IO SeekOrigin Begin     seek to the start of the NT header                          if  bReader ReadUInt32      17744    check the PE 0 0 signature                                                        fStream Seek 20  System IO SeekOrigin Current     seek past the file header                              architecture   bReader ReadUInt16      read the magic number of the optional header                                                                                                    catch  Exception       TODO  Any exception handling you want to do  personally I just take 0 as a sign of failure               if architecture returns 0  there has been an error          return architecture            Now the current constants are   0x10B - PE32  format  0x20B - PE32  format    But with this method it allows for the possibilities of new constants  just validate the return as you see fit

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TestMethod  public void EnsureKWLLibrariesAreAll64Bit         var assemblies   Assembly GetExecutingAssembly   GetReferencedAssemblies   Where x   gt  x FullName StartsWith  YourCommonProjectName    ToArray        foreach  var assembly in assemblies                var myAssemblyName   AssemblyName GetAssemblyName assembly FullName Split      0      dll            Assert AreEqual ProcessorArchitecture MSIL  myAssemblyName ProcessorArchitecture

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Look at System Reflection AssemblyName GetAssemblyName string assemblyFile   You can examine assembly metadata from the returned AssemblyName instance   Using PowerShell     36  C     reflection assemblyname   GetAssemblyName    pwd  Microsoft GLEE dll     fl  Name                    Microsoft GLEE Version                 1 0 0 0 CultureInfo             CodeBase                file    C  projects powershell BuildAnalyzer     EscapedCodeBase         file    C  projects powershell BuildAnalyzer     ProcessorArchitecture   MSIL Flags                   PublicKey HashAlgorithm           SHA1 VersionCompatibility    SameMachine KeyPair                 FullName                Microsoft GLEE  Version 1 0 0 0  Culture neut       Here  ProcessorArchitecture identifies target platform    Amd64  A 64-bit processor based on the x64 architecture  Arm  An ARM processor  IA64  A 64-bit Intel Itanium processor only  MSIL  Neutral with respect to processor and bits-per-word  X86  A 32-bit Intel processor  either native or in the Windows on Windows environment on a 64-bit platform  WOW64   None  An unknown or unspecified combination of processor and bits-per-word    I m using PowerShell in this example to call the method

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You can use the CorFlags CLI tool  for instance  C  Program Files Microsoft SDKs Windows v7 0 Bin CorFlags exe  to determine the status of an assembly  based on its output and opening an assembly as a binary asset you should be able to determine where you need to seek to determine if the 32BIT flag is set to 1  x86  or 0  Any CPU or x64  depending on PE    Option      PE      32BIT ---------- ------- --------- x86         PE32    1 Any CPU     PE32    0 x64         PE32    0   The blog post x64 Development with  NET has some information about corflags   Even better  you can use Module GetPEKind to determine whether an assembly is PortableExecutableKinds value PE32Plus  64-bit   Required32Bit  32-bit and WOW   or ILOnly  any CPU  along with other attributes

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Try to use CorFlagsReader from this project at CodePlex  It has no references to other assemblies and it can be used as is

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More generic way - use file structure to determine bitness and image type   public static CompilationMode GetCompilationMode this FileInfo info        if   info Exists  throw new ArgumentException    info FullName  does not exist         var intPtr   IntPtr Zero      try               uint unmanagedBufferSize   4096          intPtr   Marshal AllocHGlobal  int unmanagedBufferSize            using  var stream   File Open info FullName  FileMode Open  FileAccess Read                         var bytes   new byte unmanagedBufferSize               stream Read bytes  0  bytes Length               Marshal Copy bytes  0  intPtr  bytes Length                        Check DOS header magic number         if  Marshal ReadInt16 intPtr     0x5a4d  return CompilationMode Invalid              This will get the address for the WinNT header           var ntHeaderAddressOffset   Marshal ReadInt32 intPtr   60               Check WinNT header signature         var signature   Marshal ReadInt32 intPtr   ntHeaderAddressOffset           if  signature    0x4550  return CompilationMode Invalid             Determine file bitness by reading magic from IMAGE OPTIONAL HEADER         var magic   Marshal ReadInt16 intPtr   ntHeaderAddressOffset   24            var result   CompilationMode Invalid          uint clrHeaderSize          if  magic    0x10b                        clrHeaderSize    uint Marshal ReadInt32 intPtr   ntHeaderAddressOffset   24   208   4               result    CompilationMode Bit32                    else if  magic    0x20b                        clrHeaderSize    uint Marshal ReadInt32 intPtr   ntHeaderAddressOffset   24   224   4               result    CompilationMode Bit64                    else return CompilationMode Invalid           result    clrHeaderSize    0               CompilationMode CLR               CompilationMode Native           return result            finally               if  intPtr    IntPtr Zero  Marshal FreeHGlobal intPtr             Compilation mode enumeration   Flags  public enum CompilationMode       Invalid   0      Native   0x1      CLR   Native  lt  lt  1      Bit32   CLR  lt  lt  1      Bit64   Bit32  lt  lt  1     Source code with explanation at GitHub

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DotPeek from JetBrains provides quick and easy way to see msil anycpu   x86  x64

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cfeduke notes the possibility of calling GetPEKind  It s potentially interesting to do this from PowerShell   Here  for example  is code for a cmdlet that could be used  https   stackoverflow com a 16181743 64257  Alternatively  at https   stackoverflow com a 4719567 64257 it is noted that  there s also the Get-PEHeader cmdlet in the PowerShell Community Extensions that can be used to test for executable images

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More generic way - use file structure to determine bitness and image type   public static CompilationMode GetCompilationMode this FileInfo info        if   info Exists  throw new ArgumentException    info FullName  does not exist         var intPtr   IntPtr Zero      try               uint unmanagedBufferSize   4096          intPtr   Marshal AllocHGlobal  int unmanagedBufferSize            using  var stream   File Open info FullName  FileMode Open  FileAccess Read                         var bytes   new byte unmanagedBufferSize               stream Read bytes  0  bytes Length               Marshal Copy bytes  0  intPtr  bytes Length                        Check DOS header magic number         if  Marshal ReadInt16 intPtr     0x5a4d  return CompilationMode Invalid              This will get the address for the WinNT header           var ntHeaderAddressOffset   Marshal ReadInt32 intPtr   60               Check WinNT header signature         var signature   Marshal ReadInt32 intPtr   ntHeaderAddressOffset           if  signature    0x4550  return CompilationMode Invalid             Determine file bitness by reading magic from IMAGE OPTIONAL HEADER         var magic   Marshal ReadInt16 intPtr   ntHeaderAddressOffset   24            var result   CompilationMode Invalid          uint clrHeaderSize          if  magic    0x10b                        clrHeaderSize    uint Marshal ReadInt32 intPtr   ntHeaderAddressOffset   24   208   4               result    CompilationMode Bit32                    else if  magic    0x20b                        clrHeaderSize    uint Marshal ReadInt32 intPtr   ntHeaderAddressOffset   24   224   4               result    CompilationMode Bit64                    else return CompilationMode Invalid           result    clrHeaderSize    0               CompilationMode CLR               CompilationMode Native           return result            finally               if  intPtr    IntPtr Zero  Marshal FreeHGlobal intPtr             Compilation mode enumeration   Flags  public enum CompilationMode       Invalid   0      Native   0x1      CLR   Native  lt  lt  1      Bit32   CLR  lt  lt  1      Bit64   Bit32  lt  lt  1     Source code with explanation at GitHub

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Below is a batch file that will run corflags exe against all dlls and exes in the current working directory and all sub-directories  parse the results and display the target architecture of each   Depending on the version of corflags exe that is used  the line items in the output will either include 32BIT  or 32BITREQ  and 32BITPREF    Whichever of these two is included in the output is the critical line item that must be checked to differentiate between Any CPU and x86   If you are using an older version of corflags exe  pre Windows SDK v8 0A   then only the 32BIT line item will be present in the output  as others have indicated in past answers   Otherwise 32BITREQ and 32BITPREF replace it   This assumes corflags exe is in the  PATH    The simplest way to ensure this is to use a Developer Command Prompt   Alternatively you could copy it from it s default location   If the batch file below is run against an unmanaged dll or exe  it will incorrectly display it as x86  since the actual output from Corflags exe will be an error message similar to       corflags   error CF008   The specified file does not have a valid managed header    echo off  echo  echo Target architecture for all exes and dlls  echo   REM For each exe and dll in this directory and all subdirectories    for   a in   exe   dll  do forfiles  s  m    a  c  cmd  c echo  relpath   gt  testfiles txt  for  f   b in  testfiles txt  do       REM Dump corflags results to a text file     corflags  nologo   b  gt  corflagsdeets txt     REM Parse the corflags results to look for key markers       findstr  C  PE32   gt nul   corflagsdeets txt  amp  amp                REM  PE32   indicates x64         echo    b   x64                  REM pre-v8 Windows SDK listed only  32BIT  line item         REM newer versions list  32BITREQ  and  32BITPREF  line items         findstr  C  32BITREQ    0  gt nul  C  32BIT       0    corflagsdeets txt  amp  amp                REM  PE32  and NOT 32bit required indicates Any CPU             echo    b   Any CPU                            REM  PE32  and 32bit required indicates x86             echo    b   x86                      del corflagsdeets txt    del testfiles txt echo

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Just for clarification  CorFlags exe is part of the  NET Framework SDK  I have the development tools on my machine  and the simplest way for me determine whether a DLL is 32-bit only is to    Open the Visual Studio Command Prompt  In Windows  menu Start Programs Microsoft Visual Studio Visual Studio Tools Visual Studio 2008 Command Prompt  CD to the directory containing the DLL in question Run corflags like this  corflags MyAssembly dll   You will get output something like this   Microsoft  R   NET Framework CorFlags Conversion Tool   Version  3 5 21022 8 Copyright  c  Microsoft Corporation   All rights reserved   Version     v2 0 50727 CLR Header  2 5 PE          PE32 CorFlags    3 ILONLY      1 32BIT       1 Signed      0   As per comments the flags above are to be read as following    Any CPU  PE   PE32 and 32BIT   0 x86  PE   PE32 and 32BIT   1 64-bit  PE   PE32  and 32BIT   0

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cfeduke notes the possibility of calling GetPEKind  It s potentially interesting to do this from PowerShell   Here  for example  is code for a cmdlet that could be used  https   stackoverflow com a 16181743 64257  Alternatively  at https   stackoverflow com a 4719567 64257 it is noted that  there s also the Get-PEHeader cmdlet in the PowerShell Community Extensions that can be used to test for executable images

User · Answer

An alternative to already mentioned tools is Telerik JustDecompile  free tool  which will display the information next to the assembly name

User · Answer

An alternative to already mentioned tools is Telerik JustDecompile  free tool  which will display the information next to the assembly name

User · Answer

Just for clarification  CorFlags exe is part of the  NET Framework SDK  I have the development tools on my machine  and the simplest way for me determine whether a DLL is 32-bit only is to    Open the Visual Studio Command Prompt  In Windows  menu Start Programs Microsoft Visual Studio Visual Studio Tools Visual Studio 2008 Command Prompt  CD to the directory containing the DLL in question Run corflags like this  corflags MyAssembly dll   You will get output something like this   Microsoft  R   NET Framework CorFlags Conversion Tool   Version  3 5 21022 8 Copyright  c  Microsoft Corporation   All rights reserved   Version     v2 0 50727 CLR Header  2 5 PE          PE32 CorFlags    3 ILONLY      1 32BIT       1 Signed      0   As per comments the flags above are to be read as following    Any CPU  PE   PE32 and 32BIT   0 x86  PE   PE32 and 32BIT   1 64-bit  PE   PE32  and 32BIT   0

User · Answer

Another way to check the target platform of a  NET assembly is inspecting the assembly with  NET Reflector               I ve just realized that the new version is not free  So  correction  if you have a free version of  NET reflector  you can use it to check the target platform

User · Answer

One more way would be to use dumpbin from the Visual Studio tools on DLL and look for the appropriate output  dumpbin exe  HEADERS  lt your dll path gt      FILE HEADER VALUE                  14C machine  x86                     4 number of sections             5885AC36 time date stamp Mon Jan 23 12 39 42 2017                    0 file pointer to symbol table                    0 number of symbols                   E0 size of optional header                 2102 characteristics                        Executable                        32 bit word machine                        DLL   Note  Above o p is for 32bit dll  One more useful option with dumpbin exe is  EXPORTS  It will show you the function exposed by the dll  dumpbin exe  EXPORTS  lt PATH OF THE DLL gt

User · Answer

Below is a batch file that will run corflags exe against all dlls and exes in the current working directory and all sub-directories  parse the results and display the target architecture of each   Depending on the version of corflags exe that is used  the line items in the output will either include 32BIT  or 32BITREQ  and 32BITPREF    Whichever of these two is included in the output is the critical line item that must be checked to differentiate between Any CPU and x86   If you are using an older version of corflags exe  pre Windows SDK v8 0A   then only the 32BIT line item will be present in the output  as others have indicated in past answers   Otherwise 32BITREQ and 32BITPREF replace it   This assumes corflags exe is in the  PATH    The simplest way to ensure this is to use a Developer Command Prompt   Alternatively you could copy it from it s default location   If the batch file below is run against an unmanaged dll or exe  it will incorrectly display it as x86  since the actual output from Corflags exe will be an error message similar to       corflags   error CF008   The specified file does not have a valid managed header    echo off  echo  echo Target architecture for all exes and dlls  echo   REM For each exe and dll in this directory and all subdirectories    for   a in   exe   dll  do forfiles  s  m    a  c  cmd  c echo  relpath   gt  testfiles txt  for  f   b in  testfiles txt  do       REM Dump corflags results to a text file     corflags  nologo   b  gt  corflagsdeets txt     REM Parse the corflags results to look for key markers       findstr  C  PE32   gt nul   corflagsdeets txt  amp  amp                REM  PE32   indicates x64         echo    b   x64                  REM pre-v8 Windows SDK listed only  32BIT  line item         REM newer versions list  32BITREQ  and  32BITPREF  line items         findstr  C  32BITREQ    0  gt nul  C  32BIT       0    corflagsdeets txt  amp  amp                REM  PE32  and NOT 32bit required indicates Any CPU             echo    b   Any CPU                            REM  PE32  and 32bit required indicates x86             echo    b   x86                      del corflagsdeets txt    del testfiles txt echo

User · Answer

Another way to check the target platform of a  NET assembly is inspecting the assembly with  NET Reflector               I ve just realized that the new version is not free  So  correction  if you have a free version of  NET reflector  you can use it to check the target platform

User · Answer

Look at System Reflection AssemblyName GetAssemblyName string assemblyFile   You can examine assembly metadata from the returned AssemblyName instance   Using PowerShell     36  C     reflection assemblyname   GetAssemblyName    pwd  Microsoft GLEE dll     fl  Name                    Microsoft GLEE Version                 1 0 0 0 CultureInfo             CodeBase                file    C  projects powershell BuildAnalyzer     EscapedCodeBase         file    C  projects powershell BuildAnalyzer     ProcessorArchitecture   MSIL Flags                   PublicKey HashAlgorithm           SHA1 VersionCompatibility    SameMachine KeyPair                 FullName                Microsoft GLEE  Version 1 0 0 0  Culture neut       Here  ProcessorArchitecture identifies target platform    Amd64  A 64-bit processor based on the x64 architecture  Arm  An ARM processor  IA64  A 64-bit Intel Itanium processor only  MSIL  Neutral with respect to processor and bits-per-word  X86  A 32-bit Intel processor  either native or in the Windows on Windows environment on a 64-bit platform  WOW64   None  An unknown or unspecified combination of processor and bits-per-word    I m using PowerShell in this example to call the method

User · Answer

DotPeek from JetBrains provides quick and easy way to see msil anycpu   x86  x64

User · Answer

TestMethod  public void EnsureKWLLibrariesAreAll64Bit         var assemblies   Assembly GetExecutingAssembly   GetReferencedAssemblies   Where x   gt  x FullName StartsWith  YourCommonProjectName    ToArray        foreach  var assembly in assemblies                var myAssemblyName   AssemblyName GetAssemblyName assembly FullName Split      0      dll            Assert AreEqual ProcessorArchitecture MSIL  myAssemblyName ProcessorArchitecture

User · Answer

How about you just write you own  The core of the PE architecture hasn t been seriously changed since its implementation in Windows 95  Here s a C  example       public static ushort GetPEArchitecture string pFilePath                ushort architecture   0          try                       using  System IO FileStream fStream   new System IO FileStream pFilePath  System IO FileMode Open  System IO FileAccess Read                                 using  System IO BinaryReader bReader   new System IO BinaryReader fStream                                         if  bReader ReadUInt16      23117    check the MZ signature                                               fStream Seek 0x3A  System IO SeekOrigin Current     seek to e lfanew                          fStream Seek bReader ReadUInt32    System IO SeekOrigin Begin     seek to the start of the NT header                          if  bReader ReadUInt32      17744    check the PE 0 0 signature                                                        fStream Seek 20  System IO SeekOrigin Current     seek past the file header                              architecture   bReader ReadUInt16      read the magic number of the optional header                                                                                                    catch  Exception       TODO  Any exception handling you want to do  personally I just take 0 as a sign of failure               if architecture returns 0  there has been an error          return architecture            Now the current constants are   0x10B - PE32  format  0x20B - PE32  format    But with this method it allows for the possibilities of new constants  just validate the return as you see fit

User · Answer

A more advanced application for that you can find here  CodePlex - ApiChange  Examples   C  Downloads ApiChange gt ApiChange exe -CorFlags c  Windows winhlp32 exe File Name  Type  Size  Processor  IL Only  Signed winhlp32 exe  Unmanaged  296960  X86  C  Downloads ApiChange gt ApiChange exe -CorFlags c  Windows HelpPane exe File Name  Type  Size  Processor  IL Only  Signed HelpPane exe  Unmanaged  733696  Amd64

User · Answer

You can use the CorFlags CLI tool  for instance  C  Program Files Microsoft SDKs Windows v7 0 Bin CorFlags exe  to determine the status of an assembly  based on its output and opening an assembly as a binary asset you should be able to determine where you need to seek to determine if the 32BIT flag is set to 1  x86  or 0  Any CPU or x64  depending on PE    Option      PE      32BIT ---------- ------- --------- x86         PE32    1 Any CPU     PE32    0 x64         PE32    0   The blog post x64 Development with  NET has some information about corflags   Even better  you can use Module GetPEKind to determine whether an assembly is PortableExecutableKinds value PE32Plus  64-bit   Required32Bit  32-bit and WOW   or ILOnly  any CPU  along with other attributes

User · Answer

You can use the CorFlags CLI tool  for instance  C  Program Files Microsoft SDKs Windows v7 0 Bin CorFlags exe  to determine the status of an assembly  based on its output and opening an assembly as a binary asset you should be able to determine where you need to seek to determine if the 32BIT flag is set to 1  x86  or 0  Any CPU or x64  depending on PE    Option      PE      32BIT ---------- ------- --------- x86         PE32    1 Any CPU     PE32    0 x64         PE32    0   The blog post x64 Development with  NET has some information about corflags   Even better  you can use Module GetPEKind to determine whether an assembly is PortableExecutableKinds value PE32Plus  64-bit   Required32Bit  32-bit and WOW   or ILOnly  any CPU  along with other attributes

User · Answer

I ve cloned a super handy tool that adds a context menu entry for assemblies in the windows explorer to show all available info   Download here  https   github com tebjan AssemblyInformation releases

User · Answer

A more advanced application for that you can find here  CodePlex - ApiChange  Examples   C  Downloads ApiChange gt ApiChange exe -CorFlags c  Windows winhlp32 exe File Name  Type  Size  Processor  IL Only  Signed winhlp32 exe  Unmanaged  296960  X86  C  Downloads ApiChange gt ApiChange exe -CorFlags c  Windows HelpPane exe File Name  Type  Size  Processor  IL Only  Signed HelpPane exe  Unmanaged  733696  Amd64

[.net] How can I determine if a .NET assembly was built for x86 or x64?

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