lpApplicationName

lpApplicationName is a parameter used by Windows API functions such as CreateProcess to specify the executable to run. It is a pointer to a null-terminated string that identifies the module name or a fully qualified path to the executable. The value can be NULL, in which case the executable is taken from the command line buffer provided in lpCommandLine.

If lpApplicationName is non-NULL, the system uses it to locate the executable. If the string contains a path delimiter, Windows treats it as an exact path and attempts to load the file from that location. If the string contains no path, Windows searches a standard sequence: the current working directory, the system directory, the Windows directory, and the directories listed in the PATH environment variable. If the search fails, CreateProcess fails and returns an error such as ERROR_FILE_NOT_FOUND or ERROR_PATH_NOT_FOUND.

When lpApplicationName is NULL, the executable name is taken from the first token in lpCommandLine, and the same search rules apply to locate the file.

Extensions and considerations: paths longer than MAX_PATH may require extended-length paths using the \\?\ prefix; when using a non-NULL lpApplicationName, supplying an absolute path removes ambiguity and can improve security by reducing reliance on PATH. Supplying the exact path minimizes potential spoofing of launched processes.

Common usage: pass the exact path to an executable you want to run; set lpCommandLine to the arguments to pass. Example: CreateProcess(L"C:\\Program Files\\App\\app.exe", NULL, NULL, NULL, FALSE, 0, NULL, NULL, &si, &pi);