Unresolved External Symbol while trying to use bit7z library C++ / Qt - c++

Question

I've been trying to install and properly link bit7z into my C++ code as I have to do a task for my internship which concludes in automatically zipping a certain directory and sending the zip-file out as an email. Right now the email is not interesting to me as I can't even get the base program. I just keep getting the Linker Error 2019 and I don't know what to do anymore. I'll provide as much info as I can.
I use Visual Studio 2019.
My .pro file:
TEMPLATE = app
TARGET = aixLogger
DESTDIR = ./Debug
CONFIG += debug console
DEPENDPATH += .
MOC_DIR += .
OBJECTS_DIR += debug
UI_DIR += GeneratedFiles
RCC_DIR += GeneratedFiles
LIBS += -D:/local/aretz/Programmierung/git-workplace/aixLogger/Dependencies/bit7z/lib -lbit7z
INCLUDEPATH += D:/local/aretz/Programmierung/git-workplace/aixLogger/Dependencies/bit7z/include
include(aixLogger.pri)
My .h
#pragma once
#include <qwidget.h>
#include <qobject.h>
#include <bit7z.hpp>
class AIXLogger : public QWidget
{
Q_OBJECT
public slots:
public:
void CompressDir();
void Execute();
};
My .cpp
#include <QCoreApplication>
#include <string>
#include <iostream>
#include <filesystem>
#include <bit7z.hpp>
#include "main.h"
#include "bitcompressor.hpp"
namespace fs = std::filesystem;
using namespace bit7z;
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
std::string path = "C:/Users/aretz/Downloads/test";
for (const auto& entry : fs::directory_iterator(path))
std::cout << entry.path() << std::endl;
//return a.exec();
}
void AIXLogger::CompressDir() {
try {
Bit7zLibrary lib{ L"C:/Program Files/7-Zip/7z.dll" };
//BitCompressor compressor{ lib, BitFormat::Zip };
std::vector< std::wstring > files = { L"aretz/downloads/test/test1.txt", L"aretz/downloads/test/test1.txt" };
//Zip Archiv erstellen
//compressor.compress(files, L"output_archive.zip");
//Directory zippen
//compressor.compressDirectory(L"dir/path/", L"dir_archive.zip");
}
catch (const BitException& ex) {
//irgendwas mit &ex machen
}
}
void AIXLogger::Execute() {
CompressDir();
}
I'm also adding pictures of the properties I changed.
Additional DependenciesAdditional Library DirectoriesAdditional Include Directories
EDIT: Here is the actual Error I'm getting with just the line "Bit7zLibrary lib {L"C:/Program Files/7-Zip/7z.dll" };:
Error LNK2019 unresolved external symbol "public: __thiscall bit7z::Bit7zLibrary::Bit7zLibrary(class std::basic_string<wchar_t,struct std::char_traits<wchar_t>,class std::allocator<wchar_t> > const &)" (??0Bit7zLibrary#bit7z##QAE#ABV?$basic_string#_WU?$char_traits#_W#std##V?$allocator#_W#2##std###Z) referenced in function "public: void __thiscall AIXLogger::CompressDir(void)" (?CompressDir#AIXLogger##QAEXXZ) aixLogger D:\local\aretz\Programmierung\git-workplace\aixLogger\main.obj 1
Severity Code Description Project File Line Suppression State
Error LNK2019 unresolved external symbol "public: virtual __thiscall bit7z::Bit7zLibrary::~Bit7zLibrary(void)" (??1Bit7zLibrary#bit7z##UAE#XZ) referenced in function "public: void __thiscall AIXLogger::CompressDir(void)" (?CompressDir#AIXLogger##QAEXXZ) aixLogger D:\local\aretz\Programmierung\git-workplace\aixLogger\main.obj 1

Answer 1

The problem you're having is that the linker cannot find the bit7z static library.
By default, the bit7z library is built to bit7z\bin\$(PlatformShortName)\, where $(PlatformShortName) is either x86 or x64 according to your target architecture.
However, you specified a different library directory (bit7z\lib\), which is wrong (unless you changed the directory where you output the built library).
You can fix it by changing the path to $(SolutionDir)Dependencies\bit7z\bin\$(PlatformShortName)\.
Also, please note that, on x86, the default library name is just bit7z.lib, while on x64 is bit7z64.lib.