(LB3+ only!)

From the ebook, Mastering Liberty BASIC 3:
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Find a file quickly with the SearchTreeForFile function from "imagehlp" DLL. RootPath$ is a pointer to a null- terminated string that specifies the path where the function should begin searching for the file. InputPathName$ is a pointer to a null-terminated string that specifies the file for which the function will search. A program can use a partial path. OutputPathBuffer$ is a pointer to a buffer that receives the full path to the file that is found. This string is not modified if the return value is FALSE. Below is a small demo. Choose to try searching for the filename alone, or filename with partial path.

     RootPath$="c:\"
     'InputPathName$="bmp\copy.bmp" + chr$(0) 'includes partial path
     InputPathName$="liberty.exe" + chr$(0) 'filename only
     OutputPathBuffer$=space$(1023)+chr$(0)

open "imagehlp" for dll as #ih
     calldll #ih, "SearchTreeForFile",_
     RootPath$ as ptr,_
     InputPathName$ as ptr,_
     OutputPathBuffer$ as ptr,_
     ret as long
     close #ih

print "Searching (c:\) for ";InputPathName$
     if ret=0 then
     print InputPathName$;" not found."
     else
     print "Full path is ";trim$(OutputPathBuffer$)

end if
     print "Finished"
     end

See below for an example of this function as it is used in the Open Source Editor.