c++ - 链接Howard Hinnant的日期/时区库时出错

Question

我正在尝试安装Howard Hinnant's date/time zone library，以便可以制作一个在不同时区显示时间的程序。我在时区解析器中使用了霍华德的installation guide，但是鉴于我仍然不熟悉C++和一般编程，所以我认识到我可能做错了一些事情。
到目前为止，我已经从GitHub下载了源 Material ，并且我相信我已经在Visual Studio Code中成功编译了tz.cpp(同时链接到源 Material 中提供的头文件)。我没有选择自定义构建。
然后，我尝试运行以下示例程序(安装指南中提供):

#include "date/tz.h"
#include <iostream>

int
main()
{
    using namespace date;
    using namespace std::chrono;
    auto t = make_zoned(current_zone(), system_clock::now());
    std::cout << t << '\n';
}

在控制台的“问题”窗口下没有显示错误；但是，以下文本出现在终端上:

C:\Users\kburc\AppData\Local\Temp\ccqDCN6j.o: In function `main':
c:/Users/kburc/Vol 7/Documents/!Dell64docs/Programming/CPP/KJB3programs/CLClockv2/CLClockv2.cpp:26: undefined reference to `date::current_zone()'
C:\Users\kburc\AppData\Local\Temp\ccqDCN6j.o: In function `date::sys_info date::time_zone::get_info<std::chrono::duration<long long, std::ratio<1ll, 1000000000ll> > >(std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long long, std::ratio<1ll, 1000000000ll> > >) const':
c:/Users/kburc/Vol 7/Documents/!Dell64docs/Programming/CPP/KJB3programs/CLClockv2/date/tz.h:896: undefined reference to `date::time_zone::get_info_impl(std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long long, std::ratio<1ll, 1ll> > >) const'       
collect2.exe: error: ld returned 1 exit status
The terminal process "C:\WINDOWS\System32\WindowsPowerShell\v1.0\powershell.exe -Command & 'C:\Program Files\mingw-w64\x86_64-8.1.0-posix-seh-rt_v6-rev0\mingw64\bin\g++.exe' -g 'c:\Users\kburc\Vol 7\Documents\!Dell64docs\Programming\CPP\KJB3programs\CLClockv2\CLClockv2.cpp' -o 'c:\Users\kburc\Vol 7\Documents\!Dell64docs\Programming\CPP\KJB3programs\CLClockv2\CLClockv2.exe'" terminated with exit code: 1.

Terminal will be reused by tasks, press any key to close it.

[格式的道歉]
任何有关我可能做错或做不到的事情的指针将不胜感激。如有必要，乐意提供更多信息。谢谢!
编辑:这是我的 launch.json文件:

  "version": "0.2.0",
    "configurations": [
        {
            "name": "g++.exe - Build and debug active file",
            "type": "cppdbg",
            "request": "launch",
            "program": "${fileDirname}\\${fileBasenameNoExtension}.exe",
            "args": [],
            "stopAtEntry": false,
            "cwd": "${workspaceFolder}",
            "environment": [],
            "externalConsole": false,
            "MIMode": "gdb",
            "miDebuggerPath": "C:\\Program Files\\mingw-w64\\x86_64-8.1.0-posix-seh-rt_v6-rev0\\mingw64\\bin\\gdb.exe",
            "setupCommands": [
                {
                    "description": "Enable pretty-printing for gdb",
                    "text": "-enable-pretty-printing",
                    "ignoreFailures": true
                }
            ],
            "preLaunchTask": "C/C++: g++.exe build active file"
        }
    ]
}

这是我的 tasks.json文件:

{
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [

        {
            "name": "g++.exe - Build and debug active file",
            "type": "cppdbg",
            "request": "launch",
            "program": "${fileDirname}\\${fileBasenameNoExtension}.exe",
            "args": [
                "-g",
"${workspaceFolder}\\*.cpp",
"-o",
"${fileDirname}\\${fileBasenameNoExtension}.exe"
            ],
            "stopAtEntry": false,
            "cwd": "${workspaceFolder}",
            "environment": [],
            "externalConsole": false,
            "MIMode": "gdb",
            "miDebuggerPath": "C:\\Program Files\\mingw-w64\\x86_64-8.1.0-posix-seh-rt_v6-rev0\\mingw64\\bin\\gdb.exe",
            "setupCommands": [
                {
                    "description": "Enable pretty-printing for gdb",
                    "text": "-enable-pretty-printing",
                    "ignoreFailures": true
                }
            ],
            "preLaunchTask": "C/C++: g++.exe build active file"
        }
    ]
}

Answer 1

该程序已正确编译，但未链接:

In function `main':
  undefined reference to `date::current_zone()'

In function `date::sys_info date::time_zone::get_info<...>(...) const':
  undefined reference to `date::time_zone::get_info_impl(...) const'

error: ld returned 1 exit status

因此，该问题与运行该程序无关，因为该程序尚不存在。
命令行是:

g++.exe -g CLClockv2.cpp -o CLClockv2.exe

其中不包含任何链接标志( -l)，这意味着GCC在找不到所需符号时不会链接该库并产生您在上面看到的错误。通常，您还需要搜索路径标记( -L)。

我建议您在尝试手动配置IDE(如VS Code)之前先从命令行学习编译。另一个选项是Visual Studio，它预先配置了MSVC。