I'm trying to create a .dll with Visual Studios 2013. The project includes libpq functionality.
Per other stackoverflow posts, and other sources I've found on the internet, I've (as far as I'm aware) correctly added the postgres lib and include directories to the project. However, when I go to build the project, it returns a number of "unresolved external symbol" errors.
My paths are C:\Program Files\PostresSQL\9.3\... so I have them surrounded by quotation marks in the Additional Library/Include Directory fields. I've included the libpq-fe.h header file in the project... I'm just not sure what I'm doing wrong.
Another note, I can compile a test program from the command line using g++ with the -I, -L, and -lpq flags, but I'm not sure how to compile to a .dll from the command line (plus it adds complexity that I just don't want to deal with).
These are the specific errors I'm getting:
1>sql_arma.obj : error LNK2001: unresolved external symbol _PQconnectdb
1>sql_arma.obj : error LNK2001: unresolved external symbol _PQstatus
1>sql_arma.obj : error LNK2001: unresolved external symbol _PQerrorMessage
1>sql_arma.obj : error LNK2001: unresolved external symbol _PQfinish
1>C:\Users\tills13\documents\visual studio 2013\Projects\sql_arma\Release\sql_arma.dll : fatal error LNK1120: 4 unresolved externals
I have, as suggested below, included #pragma comment(lib, "libpq.lib") in the source file for my project, I still receive these errors.
I've successfully compiled the sample program by setting these project properties:
Add <pgsql install path>\include and \lib to VC++ Directories->Include and ->Library, correspondingly
Add libpq.lib to Linker->Input->Additional dependencies
This is the standard way to reference 3rd-party libs. It's just that they recommend using environment variables for their "base dirs" to avoid patching the project when it's under a VCS.
To be able to run the app from VS (both with and without debugging), I also specified PATH=%PATH%;<pgsql install path>\bin in Debugging->Environment since this dir isn't in PATH on my system.
It's not sufficient add the postgres lib directory to the project, you must also add
reference to libpq.lib. Just add this line to one of your source .cpp files:
#pragma comment(lib, "libpq.lib")
As noted by Marco A. the library must match a program bitness (32 or 64 bit): if you build 32-bit DLL (referred as Win32) you must use 32 bit library; if 64-bit (x64) - 64-bit library.
I have also faced same issue. Then I realized that I was building my application as a 32bit. I changed the target of my application to x64 and it compiled successfully
Related
I am new to programming. I want to install Glog on my Windows 10 system. I have followed the instructions found in a Stack Overflow thread with the same name.
I used cmake and Visual Studio 2015 to build the project.
First anomaly of the built file: I noticed that in the glog directory the header file "log_severity.h" was missing. To alleviate this problem, I copied the "log_severity.h" from the GitHub repository and pasted it.
http://imgur.com/QeLTnat
I then created a sample program that just initializes the logger by only using
google::InitGoogleLogging(argv[0]);
in the main.
Before compiling I direct the linker to include an additional include directory. This include directory is the one with the header files as in the second image (with the log_severity.h etc.):
http://imgur.com/yrjOIot
Yet I still receive a linking error when compiling the code:
1>Source.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) void __cdecl google::InitGoogleLogging(char const *)" (__imp_?InitGoogleLogging#google##YAXPEBD#Z) referenced in function main
1>D:\Documents\Programming\C++\Programme\GLogTest\GlogTest\x64\Debug\GlogTest.exe : fatal error LNK1120: 1 unresolved externals
What am I doing wrong?
Thanks a lot of any answers.
I solved it. When you build the project in visual studio, there is also an "Installation" folder inside the MS project. I forgot to build that as well!
I have a makefile project in my system. Recently, I added some new functions which makes use of the following Windows APIs:
RegOpenKeyEx
RegEnumKeyEx
RegCloseKey
RegGetValue
For having those APIS I added the windows.h header file as well.
The code compiles and links fine in my machine. But, linking fails in my colleagues machine. We all are working on 64 bit windows machine.
In his PC I get the error:
error LNK2001: unresolved external symbol __imp_RegOpenKeyExW
error LNK2001: unresolved external symbol __imp_RegGetValueW
error LNK2001: unresolved external symbol __imp_RegCloseKey
error LNK2001: unresolved external symbol __imp_RegEnumKeyExW
What I tried:
Since the library being used was Advapi32.lib in C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\Lib\x64
I tried adding following line:
LINKFLAGS += -L "C:\Program Files (x86)\Microsoft
SDKs\Windows\v7.0A\Lib\x64"
I added the path of the library to environment variable PATH
I copied the lib to the output folder.
Nothing worked.
As I said earlier, the code works fine in my PC but fails in another one.
The registry functions require you to pass Advapi32.lib to the linker. This is the step that you have missed.
If you are using visual stdio, check your project property vs your friend's project property and check link library path+ library name with .lib shoul be included. It seems in your friends computer is not getting the library to resolve the symbols. Compile time checking is done only with header files. While linking it should find the definition of yor function in library.
for command line:
from:http://social.msdn.microsoft.com/Forums/vstudio/en-US/6bcae3d1-85b6-471d-a4ee-7b455b21460b/how-do-i-link-libraries-that-are-sitting-in-different-directories-from-the-command-line?forum=vcgeneral
cl main.obj ab1.lib ab2.lib de1.lib de2.lib gh1.lib /Fetestmain.exe /link /LIBPATH:C:\test\ab /LIBPATH:C:\test\de /LIBPATH:C:\test\gh
The "/link" is very important...do not use "/LINK", the uppercase LINK is not recognised.
I'm currently following the openglbook.com tutorials (set up) (Tutorial) and have run into an issue fairly early on. I'm getting the following two errors:
1>main.obj : error LNK2019: unresolved external symbol __imp__glewGetErrorString#4 referenced in function _Initialize
1>main.obj : error LNK2019: unresolved external symbol __imp__glewInit#0 referenced in function _Initialize
I have downloaded and compiled freeglut 2.8.0 as well as the glew 1.9.0 binaries. I have copied the libs and includes to C:\Program Files (x86)\Microsoft SDKs\Windows\v6.0A\Lib and Include respectively.
The Lib and Include paths have also been added to my project properties under Additional Library/Include directories.
I have also defined glew32.lib and freeglut.lib in my linker->Input->Additional dependencies.
I have included GL/glew.h and GL/freeglut.h at the top of my main file.
What am I missing? Every other thread I've found has been solved by adding the directories to the project properties. Does anyone have any ideas?
This means that you try to use GLEW as a DLL (because your application looks for a name that begins with __imp, like "import" ), but you didn't built GLEW as a DLL (because otherwise it would work).
3 possible options :
Rebuild GLEW with the GLEW_BUILD preprocessor definition (Project->Properties->C++->Preprocessor->Additional definitions). Then rebuild your application.
Don't build GLEW at all. Simply put glew.c in your application's project. This is the easiest way.
(my favourite) Define GLEW_STATIC in your application's preprocessor definitions, and rebuild.
I have been at this for some time now. I hope someone can tell me what I am doing wrong.
These are the steps I have taken so far:
-Downloaded the latest version of cURL (7.21.7).
-Opened the solution in Visual Studio 2010 using the vc6curl.dsw and converted the projects to VS2010.
-Set the libcurl project configuration to "release" and built. Build succeeded.A folder called "LIB-Release" is created. It contains several obj files and the "libcurl.lib" file resides here as well.
Test Application:
-In the project's settings I pointed the compiler to the curl includes (headers).
C/C++ >> General >> Additional Include Directories
-Added "CURL_STATICLIB" to the preprocessor definitions
C/C++ >> Preprocessor Definitions
-Added the path to the "libcurl.lib" folder in my linker additional library dependencies
Link >> General >> Additional Library Directories
-Added "libcurl.lib" to my linker additional dependencies
Link >> Input >> Additional Dependencies
-Set my projects configuration to "Realease" and hit build!
I get 42 unresolved externals errors:
Error 65 error LNK1120: 42 unresolved
externals C:\Users\Nick\Documents\Visual Studio
2010\Projects\curl_static_lib\Release\curl_static_lib.exe curl_static_lib
Error 61 error LNK2001: unresolved external symbol
___WSAFDIsSet#8 C:\Users\Nick\Documents\Visual Studio
2010\Projects\curl_static_lib\curl_static_lib\libcurl.lib(select.obj) curl_static_lib
Error 59 error LNK2001: unresolved external symbol
_imp_accept#12 C:\Users\Nick\Documents\Visual Studio
2010\Projects\curl_static_lib\curl_static_lib\libcurl.lib(ftp.obj) curl_static_lib
Error 46 error LNK2001: unresolved external symbol
_imp_ber_free C:\Users\Nick\Documents\Visual Studio
2010\Projects\curl_static_lib\curl_static_lib\libcurl.lib(ldap.obj) curl_static_lib
Error 26 error LNK2001: unresolved external symbol
_imp_bind#12 C:\Users\Nick\Documents\Visual Studio
2010\Projects\curl_static_lib\curl_static_lib\libcurl.lib(connect.obj) curl_static_lib
I have tried building using the "Debug" configuration as well. Can someone please tell me where I am going wrong?
The best way to build CURL for windows is to use NMake with provided Makefiles.
You can
Modify Makefile in root folder of CURL to set VC version you use and then run nmake vc-all (or choose any other VC target suitable for you). Check "Win32" section of ./docs/INSTALL file.
Use Makefile.vc from ./winbuild folder. Check ./winbuild/BUILD.WINDOWS.txt on how to use it.
These errors mean that there are functions that libcurl uses that are not in any of the import libraries specified in your linker config.
Sounds like at least the sockets import lib (ws2_32.lib) should be there.
Note that if you compile libcurl as a DLL then all the import libraries are specified as part of the linking of the DLL, so your application then does not need to import all these libraries and just needs to link against the curl import lib. The fact that you chose to compile curl as a static lib makes the curl code part of your application so all the support libs must be provided in your app's linker config.
I am trying to build an xll addin for Excel using appropriate framwork downloaded from MS website. I am getting the following linker errors:
1>FRAMEWRK.obj : error LNK2001: unresolved external symbol _Excel4
1>FRAMEWRK.obj : error LNK2001: unresolved external symbol _Excel4v#16
I think that these should be defined in XLCALL32.LIB included in the package from MS, but I don't know how to check it. Moreover, added the folder containing this library to the Additional Library Directories, without luck.
Hence my questions:
(1) How can I check what is in XLCALL32.LIB?
(2) How can I see which files the linker is using to see if my library is actually included?
In your project properties, Under Configuration Properties->Linker->Input, you will see 'Additional Dependencies' - these are the files the linker is using. Assuming that _Excel4 and _Excel4v are defined in XLCALL32.LIB (which I think they are), you simply need to ensure that this file is specified in this list.