How to open .dll files to see what is written inside?

I lost the solution of class-library, can I open .dll file which is created by class-library.

you are better off with a decompiler like redgates .net reflector or jetbrains resharper decompiler. there are open source ones also like

http://www.jetbrains.com/decompiler/

http://ilspy.net/

Follow below steps..

1. Go to Start Menu.
2. Type Visual Studio Tool.
3. Go to the folder above.
4. Click on "Developer Command Prompt for VS 2013" in the case of VS 2013 or just "Visual Studio Command Prompt " in case of VS 2010.
5. After command prompt loaded to screen type ILDASM.EXE press ENTER.
6. ILDASM window will open.Drag the .dll file to window from your folder.Or click on File->New.Then Add required .dll file.
7. After above steps Mainfest and .dll file will appear. Double click on these files to see what it contains.

I think you have downloaded the .NET Reflector & this FileGenerator plugin http://filegenreflector.codeplex.com/ , If you do,

1. Open up the Reflector.exe,

2. Go to View and click Add-Ins,

3. In the Add-Ins window click Add...,

4. Then find the dll you have downloaded

5. FileGenerator.dll (witch came wth the FileGenerator plugin),

6. Then close the Add-Ins window.

7. Go to File and click Open and choose the dll that you want to decompile,

8. After you have opend it, it will appear in the tree view,

9. Go to Tools and click Generate Files(Crtl+Shift+G),

10. select the output directory and select appropriate settings as your wish, Click generate files.

OR

use http://ilspy.net/

You cannot get the exact code, but you can get a decompiled version of it.

The most popular (and best) tool is Reflector, but there are also other .Net decompilers (such as Dis#).

You can also decompile the IL using ILDASM, which comes bundled with the .Net Framework SDK Tools.

I use the Jetbrains Dot peek Software , you can try that too

Telerik's Just Decompile is the best I've used. It's free once you sign up with an email.

enter link description here

Open .dll file with visual studio. Or resource editor.

*.dll files are archive files open with winzip/7zip etc. That isnt to say that all .dll files are archives you can save anything with the .dll extension however most windows .dll files are generated to be archives examples of this are windows>twain_32.dll which is an archive file however twain.dll is not if you look at twain.dll you will see an MZŽ as the first three notepad characters which denotes a Compiled C file/program or part of a program. Whereas MZ seems to be an archive.

Also most .exe files are archives mostly containing an icon image etc for the file and the windows installer packages as well they contain all the information the program needs to run images,movies etc and also directories including installation information and plain text file.

I have a game here game.exe and it contains java class files an image a pointer directing the .exe to run a .bat file. Obviously your .bat file will run a javac call from the archive and run the game there is also a few .dll archives containing java class files also.

[autorun]
ICON=AUTORUN\MINCRAFTLOGO.ICO

standard icon redirect here .ico is an image file within a .dll file within a .exe file. So the image seen on the .exe file is the minecraft logo. This is in a file called autorun.inf. Second example

[discstarter]
    startpage=Autostart\Disk1.html
    uselanguagestartpage=1
    windowcaption=Solid Edge
    licensee=Siemens PLM Software
    productguid=05B227DF-DB00-4934-B3C8-40B7D8FAA54A
    singleinstance=1
    hidesplashscreen=1
    noscrollbars=0
    showstatusbar=1
    splashscreentime=0
    windowwidth=750
    windowheight=775
    buttondir=Autostart
    toolbarcolor=16777215
    toolbar=goback,goforward,gohome,print,exit
    [autorun]
    open=autostart.exe
    icon=Autostart\ENGINE.ICO

This is the solid edge autorun.inf file contained in solidedge.exe Autostart\ is the Autostart.dll directory. open=autostart.exe specifies the autostart.exe file to run from within the original solidedge.exe archive. Here is a sample program using the .dll (dynamic link library) files http://www.flipcode.com/archives/Creating_And_Using_DLLs.shtml.

It also shows how they are created. As you can see the contents of the dll file is called by an exe file as I previously explained also there is a tutorial here http://msdn.microsoft.com/en-us/library/ms235636.aspx and as i said before 7zip or winzip will open a dynamic link library as an archive as long as you have the .dll file. If the contents of the dynamic link library have been compiled obviously you need a program which can read the file.

However since .dll files are by definition just archive library files the dll itself should be readable and not a compiled C,C# file etc etc Basically .dll files are archives well should be when a .dll file is created in visual studio the dll is created and any information you store in the dll file is encrypted. Mostly this encryption is handled by visual studio itself and generally isn't edited by hand. When you read a .dll file contents as a .exe the contents are automatically decrypted. Now when we talk about compiling a program we are changing the contents into bytecode the machine easily interprets.

This filesize would be smaller than the original file of the same contents. However the filesize is larger suggesting that the file has actually been encrypted. Probably to stop people reading their code. As a result the reading of .dll contents is termed decryption and not decompilation. Decompilation would convert the already compiled txt files to unreadable byte code. The use of standard .dll files is by definition not opensource because it involves the deliberate obfuscation of byte code.