c# - Marshalling LPWSTR * from a C function -


i have sample function native code 

hresult getsamplefunctionvalue(_out_ lpwstr * argument)

this function outputs value in argument. need call managed code

[dllimport("mydll.dll", entrypoint = "getsamplefunctionvalue", charset = charset.unicode)] static extern uint getsamplefunctionvalue([marshalasattribute(unmanagedtype.lpwstr)] stringbuilder  argument);

this returns garbage value. afaik original c function not create string using cotaskmemalloc. correct call?

any appreciated.

you need c# code receive pointer. this:

[dllimport("mydll.dll")] static extern uint getsamplefunctionvalue(out intptr argument);

call this:

intptr argument; uint retval = getsamplefunctionvalue(out argument); // add check of retval here string argstr = marshal.ptrtostringuni(argument);

and you'll presumably need call native function deallocates memory allocated. can after call marshal.ptrtostringuni because @ point no longer need pointer. or perhaps string returned statically allocated, can't sure. in case, docs native library explain what's needed.

you may need specify calling convention. written, native function looks use __cdecl. however, perhaps didn't include specification of __stdcall in question. again, consult native header file sure.


Comments

Post a Comment

Popular posts from this blog

image - ClassNotFoundException when add a prebuilt apk into system.img in android -

i'm in trouble add prebuilt apk system.img based taiwan mtk android phone platform, when push apk onto device,after reboot phone,the apk can installed succecessfully,but if add apk alps/out/target/product/$prj/system/app or vendor/mediatek/$prj/artifacts/out/target/product/$prj/system/app ,and produce system.img,the apk can't installed normally,the logcat say: a.lang.runtimeexception: unable instantiate activity componentinfo{com.sec.android.widgetapp.ap.hero.accuweather.widget/com.sec.android.widgetapp.ap.hero.accuweather.widget.weatherclock}: java.lang.classnotfoundexception: com.sec.android.widgetapp.ap.hero.accuweather.widget.weatherclock. can tell me what's problem ? when package manager installs apps part of system partition different installing apps on data partition. looks app using libraries somewhere else. when install on data lib directory created in apps data directory , symlinked /data/app-lib/. when apps installed on system it's expecte...
Read more

I need to import mysql 5.1 to 5.5? -

i have mysql 5.1 database , need import localhost running 5.5. how import 5.5 or downgrade mysql? install phpmyadmin 5.1 os: http://www.wikihow.com/install-phpmyadmin-on-your-windows-pc or https://www.digitalocean.com/community/articles/how-to-install-and-secure-phpmyadmin-on-ubuntu-12-04 then login, click on database, hit export, , export in sql format (quick fine). import .sql file 5.5 server (after installing phpmyadmin) logging in clicking database , hit import. hope helps!
Read more

Java, Hibernate, MySQL - store UTC date-time -

i saw here on few related questions (like this one , of course, this one )... essentially, want store date-time utc, , let application user choose time zone wants display date-time in. since seems date-time fields affected underlying jdbc driver, wonder if acceptable way go storing utc date-time: set both mysql , application server machine utc time zone (no need separate) both mysql , jvm should pick underlying system time settings (if not instructed otherwise) use datetime table columns on mysql side use java.util.date corresponding mapping on hibernate side (i guess java.sql.timestamp used too) let application worry interpreting date-time fields - i.e. let user choose preferred time zone is ok? edit clarify - here meant refer timestamps created strictly on server (e.g.date-time of record creation). application server instantiates date objects (new date() equals current date-time on server, , time zone agnostic). if client user wants supply date searching/filte...
Read more