DLL search on windows

Edit: As explained by Bob, this answer describes the Alternate Search Order, which is not what most applications would see. The full rules are quite complex. I don't think I can summarize them here. Instead, read the Microsoft docs - https://docs.microsoft.com/en-us/windows/win32/dlls/dynamic-link-library-search-order

My original answer was:

This MSDN article explains the default search order. I quote:

1. The directory specified by lpFileName.
2. The system directory. Use the GetSystemDirectory function to get the path of this directory.
3. The 16-bit system directory. There is no function that obtains the path of this directory, but it is searched.
4. The Windows directory. Use the GetWindowsDirectory function to get the path of this directory.
5. The current directory.
6. The directories that are listed in the PATH environment variable. Note that this does not include the per-application path specified by the App Paths registry key. The App Paths key is not used when computing the DLL search path.

In (1), if you statically linked against the DLL's stub library, I think "the directory specified by lpFileName" is the process's exe's path.

Take a look at the help for the LoadLibrary and CreateProcess functions. These describe the paths used to locate DLLs, and how you can modify them.