链接Howard Hinnant的日期/时区库时出错

如何解决链接Howard Hinnant的日期/时区库时出错

我正在尝试安装Howard Hinnant's date/time zone library，以便使我的程序可以显示不同时区的时间。我在时区解析器中使用的是霍华德的installation guide，但是鉴于我仍然不熟悉C ++和一般编程，所以我意识到我做错了某些事情。

到目前为止，我已经从GitHub下载了源资料，并且我相信我已经在Visual Studio Code中成功编译了tz.cpp（同时链接到源资料中提供的头文件）。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';
}

控制台上的“问题”窗口下没有显示错误；但是，终端上会显示以下文本：


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,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,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","args": [
                "-g","${workspaceFolder}\\*.cpp","-o","${fileDirname}\\${fileBasenameNoExtension}.exe"
            ],"preLaunchTask": "C/C++: g++.exe build active file"
        }
    ]
}

解决方法

该程序已正确编译，但未链接：

package com.example;

import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
public class Application {

    @RestController
    public static class HelloController {

        @RequestMapping("/")
        public String local() {
            return "Greetings from Local!";
        }

    }

}

因此，该问题与运行该程序无关，因为该程序尚不存在。

命令行为：

package com.example;

import io.cucumber.java.en.Given;
import io.cucumber.junit.platform.engine.Cucumber;
import io.cucumber.spring.CucumberContextConfiguration;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.web.servlet.MockMvc;

import static org.hamcrest.CoreMatchers.equalTo;
import static org.springframework.http.MediaType.APPLICATION_JSON;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;

@Cucumber
@CucumberContextConfiguration
@SpringBootTest
@AutoConfigureMockMvc
public class CucumberTest {

    @Autowired
    private MockMvc mvc;

    @Given("the application says hello")
    public void getLocalHello() throws Exception {
        mvc.perform(get("/").accept(APPLICATION_JSON))
                .andExpect(status().isOk())
                .andExpect(content().string(equalTo("Greetings from Local!")));
    }

}

其中不包含任何链接标志（Feature: Hello world Scenario: Calling a rest end point * the application says hello），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，您也需要搜索路径标记（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）。

我建议您先尝试从命令行进行编译，然后再尝试手动配置VS Code之类的IDE。另一个选项是预先配置了MSVC的Visual Studio。

更新：部分得益于Acorn的反馈，我能够使程序按需运行。原来，我需要进行一些更改。

首先，我需要在程序中包含tz.cpp。

第二，我需要编辑构建命令，不仅添加tz.cpp，而且还添加-lole32（要指出这一点，请在https://github.com/HowardHinnant/date/issues/272放行）。这可以在命令提示符下完成 g++ CLClockv2.cpp tz.cpp -lole32 -o CLClockv2.exe 或在Visual Studio Code中使用以下task.json文件：

{
    "version": "2.0.0","tasks": [
        {
            "type": "shell","label": "C/C++: g++.exe build active file","command": "C:\\Program Files\\mingw-w64\\x86_64-8.1.0-posix-seh-rt_v6-rev0\\mingw64\\bin\\g++.exe","args": [
                "-g","${workspaceFolder}\\*.cpp","-lole32","-o","${fileDirname}\\${fileBasenameNoExtension}.exe"
            ],"options": {
                "cwd": "${workspaceFolder}"
            },"problemMatcher": [
                "$gcc"
            ],"group": {
                "kind": "build","isDefault": true
            }
        }
    ]
}

但是，我然后发现我需要从https://www.iana.org/time-zones下载时区数据库的副本（“仅数据”版本对我有用），然后将其解压缩到名为tzdata的下载文件夹中。

最后，我需要创建一个名为windowsZones.xml的文件（在https://github.com/unicode-org/cldr/blob/master/common/supplemental/windowsZones.xml上提供）并将其包含在downloads文件夹中。

一旦执行了所有这些步骤，便可以使程序正常工作。

再次感谢您的帮助！

肯

链接Howard Hinnant的日期/时区库时出错

如何解决链接Howard Hinnant的日期/时区库时出错

解决方法

相关推荐