how to locate dll in native c++ world / dotnet world?

總結：

1. 對於native c++ world來說，Dynamic-Link Library Search Order 說的很清楚了。就是還有一個疑問：如果在任意目錄建立一新folder，把一個application需要的plugin之類的dll及dependency dlls都放在裡面，在load這個plugin需要的dependency dlls時 （If a DLL with dependencies is loaded by specifying a full path, the system searches for the DLL's dependent DLLs as if they were loaded with just their module names.）這個新的folder會被search到嗎？

2. 對於dotnet world，首先理解有兩個application級的檔案：app.exe.manifest, app.exe.config。 然後，關於runtime CLR如何locate assembly，這篇How the Runtime Locates Assemblies 是全面的介紹。The simple version is that the GAC is searched firstly, and then the app path tree. %PATH% is never used.  相關基礎知識：

    1）In dotnet world, A private assembly is stored in the application’s directory and used by a single application. A share assembly can be used by multiple applications and is stored in the Global assembly cache, a repository of assemblies maintained by the .Net Framework.

    2）GAC 和sidebyside的區別，本blog裡有詳細介紹。

    3）如果你確實需要把一個app的private assembly（一定程度上算，但絕對算不是放在GAC裡的資格）搬出app path來放，MS還提供了一套機制來協助你定位assembly成功：AssemblyResolver。具體介紹，參見本blog AssemblyResolver。 

    4）use Assembly Binding Log Viewer (Fuslogvw.exe) to debug any assembly loading problems.

 

參考: In what order are locations searched to load referenced DLLs?