如何解决这个或多个被多重定义的符号找到的错误？
如何解决这个或多个被多重定义的符号找到的错误？
提问于 2021-10-30 10:19:57
以下项目中的错误是什么？
main.cpp
#include "template_specialization_conflict_test.hpp"
int main()
{
std::cout << utils::my_template_function(0.555);
std::cout<<utils::my_template_function<double>(0.555);
return 0;
}template_specialization_conflict_test.hpp
#ifndef UTILS__UTILS__UTILS__UTILS
#define UTILS__UTILS__UTILS__UTILS
#include <iostream>
namespace utils
{
// A generic function
template <class T>
T my_template_function(T parameter)
{
std::cout << "function template";
std::cout << parameter;
return parameter;
}
// Template Specialization
// A function specialized for double data type
template <>
double my_template_function<double>(double parameter)
{
std::cout << "function specialization on double";
std::cout << parameter;
return parameter;
}
}
#endiftemplate_specialization_conflict_test.cpp
#include "template_specialization_conflict_test.hpp"
namespace utils
{
//empty
}误差
>------ Rebuild All started: Project: template_specialization_conflict_test, Configuration: x64-Debug ------
[1/1] Cleaning all built files...
Cleaning... 2 files.
[1/3] Building CXX object CMakeFiles\template_specialization_conflict_test.dir\main.cpp.obj
[2/3] Building CXX object CMakeFiles\template_specialization_conflict_test.dir\template_specialization_conflict_test.cpp.obj
[3/3] Linking CXX executable template_specialization_conflict_test.exe
FAILED: template_specialization_conflict_test.exe
cmd.exe /C "cd . && "C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\Common7\IDE\CommonExtensions\Microsoft\CMake\CMake\bin\cmake.exe" -E vs_link_exe --intdir=CMakeFiles\template_specialization_conflict_test.dir --rc=C:\PROGRA~2\WI3CF2~1\10\bin\10.0.17763.0\x64\rc.exe --mt=C:\PROGRA~2\WI3CF2~1\10\bin\10.0.17763.0\x64\mt.exe --manifests -- "C:\PROGRA~2\Microsoft Visual Studio\2019\Professional\VC\Tools\MSVC\14.29.30133\bin\Hostx64\x64\link.exe" /nologo CMakeFiles\template_specialization_conflict_test.dir\template_specialization_conflict_test.cpp.obj CMakeFiles\template_specialization_conflict_test.dir\main.cpp.obj /out:template_specialization_conflict_test.exe /implib:template_specialization_conflict_test.lib /pdb:template_specialization_conflict_test.pdb /version:0.0 /machine:x64 /debug /INCREMENTAL /subsystem:console kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib && cd ."
LINK Pass 1: command "C:\PROGRA~2\Microsoft Visual Studio\2019\Professional\VC\Tools\MSVC\14.29.30133\bin\Hostx64\x64\link.exe /nologo CMakeFiles\template_specialization_conflict_test.dir\template_specialization_conflict_test.cpp.obj CMakeFiles\template_specialization_conflict_test.dir\main.cpp.obj /out:template_specialization_conflict_test.exe /implib:template_specialization_conflict_test.lib /pdb:template_specialization_conflict_test.pdb /version:0.0 /machine:x64 /debug /INCREMENTAL /subsystem:console kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib /MANIFEST /MANIFESTFILE:CMakeFiles\template_specialization_conflict_test.dir/intermediate.manifest CMakeFiles\template_specialization_conflict_test.dir/manifest.res" failed (exit code 1169) with the following output:
C:\Users\pc\source\repos\template_specialization_conflict_test\out\build\x64-Debug\main.cpp.obj : error LNK2005: "double __cdecl utils::my_template_function<double>(double)" (??$my_template_function@N@utils@@YANN@Z) already defined in template_specialization_conflict_test.cpp.obj
C:\Users\pc\source\repos\template_specialization_conflict_test\out\build\x64-Debug\template_specialization_conflict_test.exe : fatal error LNK1169: one or more multiply defined symbols found
ninja: build stopped: subcommand failed.
Rebuild All failed.我怎么才能解决这个问题？
回答 1
Stack Overflow用户
回答已采纳
发布于 2021-10-30 11:09:26
我怎么才能解决这个问题？
您可以通过为专门化添加/使用关键字inline来解决这个问题，因此专门化如下所示：
//note the keyword inline in the below specialization
template <> inline
double my_template_function<double>(double parameter)
{
std::cout << "function specialization on double";
std::cout << parameter;
return parameter;
}这是可以看到这里的工作方式。
第二种解决这个问题的方法是将您的专门化移到源文件中而不是头文件中。所以你的template_specialization_conflict_test.cpp看起来应该是：template_specialization_conflict_test.cpp
#include "template_specialization_conflict_test.hpp"
namespace utils
{
// Template Specialization
// A function specialized for double data type
template <>
double my_template_function<double>(double parameter)
{
std::cout << "function specialization on double";
std::cout << parameter;
return parameter;
}
}该程序的工作方式可以看到这里和这里( gcc和clang)。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/69778684
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