Question

我试图在linux上编译我的程序。它在Windows上运行良好（在Visual Studio 2015下编译）。但是当我尝试在Linux上做同样的事情时，我得到了这个错误：

g++ -std=c++0x -std=c++0x    Prueba1.cpp   -o Prueba1
/tmp/cc9HTgYi.o: In function `Escuchador::onFrame(Leap::Controller const&)':
Prueba1.cpp:(.text+0x51): undefined reference to `Leap::Controller::frame(int) const'
Prueba1.cpp:(.text+0x6c): undefined reference to `Leap::Frame::fingers() const'
Prueba1.cpp:(.text+0x7d): undefined reference to `Leap::FingerList::count() const'
Prueba1.cpp:(.text+0x97): undefined reference to `Leap::Frame::hands() const'
Prueba1.cpp:(.text+0xa8): undefined reference to `Leap::HandList::count() const'
Prueba1.cpp:(.text+0xbc): undefined reference to `Leap::Frame::timestamp() const'
Prueba1.cpp:(.text+0xce): undefined reference to `Leap::Frame::id() const'
Prueba1.cpp:(.text+0x1ac): undefined reference to `Leap::Frame::hands() const'
Prueba1.cpp:(.text+0x1c7): undefined reference to `Leap::HandList::begin() const'
Prueba1.cpp:(.text+0x203): undefined reference to `Leap::Hand::isLeft() const'
Prueba1.cpp:(.text+0x245): undefined reference to `Leap::Hand::id() const'
Prueba1.cpp:(.text+0x2fc): undefined reference to `Leap::Hand::palmNormal() const'
Prueba1.cpp:(.text+0x317): undefined reference to `Leap::Hand::direction() const'
Prueba1.cpp:(.text+0x332): undefined reference to `Leap::Hand::fingers() const'
Prueba1.cpp:(.text+0x34d): undefined reference to `Leap::FingerList::begin() const'
Prueba1.cpp:(.text+0x37e): undefined reference to `Leap::Pointable::id() const'
Prueba1.cpp:(.text+0x38e): undefined reference to `Leap::Finger::type() const'
Prueba1.cpp:(.text+0x47b): undefined reference to `Leap::Finger::bone(Leap::Bone::Type) const'
Prueba1.cpp:(.text+0x510): undefined reference to `Leap::Frame::hands() const'
Prueba1.cpp:(.text+0x533): undefined reference to `Leap::HandList::operator[](int) const'
Prueba1.cpp:(.text+0x54e): undefined reference to `Leap::Hand::fingers() const'
Prueba1.cpp:(.text+0x582): undefined reference to `Leap::FingerList::begin() const'
Prueba1.cpp:(.text+0x595): undefined reference to `Leap::Bone::Bone()'
Prueba1.cpp:(.text+0x5ea): undefined reference to `Leap::Finger::bone(Leap::Bone::Type) const'
Prueba1.cpp:(.text+0x63e): undefined reference to `Leap::Finger::type() const'
Prueba1.cpp:(.text+0x67f): undefined reference to `Leap::operator<<(std::ostream&, Leap::Bone const&)'
Prueba1.cpp:(.text+0x6ee): undefined reference to `Leap::FingerList::end() const'
Prueba1.cpp:(.text+0x726): undefined reference to `Leap::Hand::fingers() const'
Prueba1.cpp:(.text+0x74d): undefined reference to `Leap::FingerList::begin() const'
Prueba1.cpp:(.text+0x768): undefined reference to `Leap::FingerList::end() const'
Prueba1.cpp:(.text+0x7ab): undefined reference to `Leap::Finger::bone(Leap::Bone::Type) const'
Prueba1.cpp:(.text+0x7ce): undefined reference to `Leap::Finger::bone(Leap::Bone::Type) const'
Prueba1.cpp:(.text+0x7f1): undefined reference to `Leap::Finger::bone(Leap::Bone::Type) const'
Prueba1.cpp:(.text+0x814): undefined reference to `Leap::Finger::bone(Leap::Bone::Type) const'
Prueba1.cpp:(.text+0x825): undefined reference to `Leap::Finger::type() const'
Prueba1.cpp:(.text+0x848): undefined reference to `Leap::Bone::direction() const'
Prueba1.cpp:(.text+0x863): undefined reference to `Leap::Bone::direction() const'
Prueba1.cpp:(.text+0x89e): undefined reference to `Leap::Bone::direction() const'
Prueba1.cpp:(.text+0x8b9): undefined reference to `Leap::Bone::direction() const'
Prueba1.cpp:(.text+0x8f4): undefined reference to `Leap::Bone::direction() const'
/tmp/cc9HTgYi.o:Prueba1.cpp:(.text+0x90c): more undefined references to `Leap::Bone::direction() const' follow
/tmp/cc9HTgYi.o: In function `Escuchador::onFrame(Leap::Controller const&)':
Prueba1.cpp:(.text+0xa15): undefined reference to `Leap::Finger::type() const'
Prueba1.cpp:(.text+0xa37): undefined reference to `Leap::Bone::direction() const'
Prueba1.cpp:(.text+0xa4f): undefined reference to `Leap::Bone::direction() const'
Prueba1.cpp:(.text+0xa87): undefined reference to `Leap::Bone::direction() const'
Prueba1.cpp:(.text+0xa9f): undefined reference to `Leap::Bone::direction() const'
Prueba1.cpp:(.text+0xad7): undefined reference to `Leap::Bone::direction() const'
/tmp/cc9HTgYi.o:Prueba1.cpp:(.text+0xaef): more undefined references to `Leap::Bone::direction() const' follow
/tmp/cc9HTgYi.o: In function `Escuchador::onFrame(Leap::Controller const&)':
Prueba1.cpp:(.text+0xbf8): undefined reference to `Leap::Finger::type() const'
Prueba1.cpp:(.text+0xc1b): undefined reference to `Leap::Bone::direction() const'
Prueba1.cpp:(.text+0xc33): undefined reference to `Leap::Bone::direction() const'
Prueba1.cpp:(.text+0xc6b): undefined reference to `Leap::Bone::direction() const'
Prueba1.cpp:(.text+0xc83): undefined reference to `Leap::Bone::direction() const'
Prueba1.cpp:(.text+0xcbb): undefined reference to `Leap::Bone::direction() const'
/tmp/cc9HTgYi.o:Prueba1.cpp:(.text+0xcd3): more undefined references to `Leap::Bone::direction() const' follow
/tmp/cc9HTgYi.o: In function `Escuchador::onFrame(Leap::Controller const&)':
Prueba1.cpp:(.text+0xeb4): undefined reference to `Leap::FingerList::end() const'
Prueba1.cpp:(.text+0xf27): undefined reference to `Leap::HandList::end() const'
/tmp/cc9HTgYi.o: In function `main':
Prueba1.cpp:(.text+0x11a3): undefined reference to `Leap::Controller::Controller()'
Prueba1.cpp:(.text+0x11b7): undefined reference to `Leap::Controller::addListener(Leap::Listener&)'
Prueba1.cpp:(.text+0x11fb): undefined reference to `Leap::Controller::removeListener(Leap::Listener&)'
Prueba1.cpp:(.text+0x120c): undefined reference to `Leap::Controller::~Controller()'
Prueba1.cpp:(.text+0x122a): undefined reference to `Leap::Controller::~Controller()'
/tmp/cc9HTgYi.o: In function `Leap::Pointable::~Pointable()':
Prueba1.cpp:(.text._ZN4Leap9PointableD2Ev[_ZN4Leap9PointableD5Ev]+0x16): undefined reference to `Leap::Interface::~Interface()'
/tmp/cc9HTgYi.o: In function `Leap::Bone::operator=(Leap::Bone&&)':
Prueba1.cpp:(.text._ZN4Leap4BoneaSEOS0_[_ZN4Leap4BoneaSEOS0_]+0x14): undefined reference to `Leap::Interface::operator=(Leap::Interface const&)'
/tmp/cc9HTgYi.o: In function `Leap::ConstListIterator<Leap::HandList, Leap::Hand>::operator*() const':
Prueba1.cpp:(.text._ZNK4Leap17ConstListIteratorINS_8HandListENS_4HandEEdeEv[_ZNK4Leap17ConstListIteratorINS_8HandListENS_4HandEEdeEv]+0x20): undefined reference to `Leap::HandList::operator[](int) const'
/tmp/cc9HTgYi.o: In function `Leap::ConstListIterator<Leap::FingerList, Leap::Finger>::operator*() const':
Prueba1.cpp:(.text._ZNK4Leap17ConstListIteratorINS_10FingerListENS_6FingerEEdeEv[_ZNK4Leap17ConstListIteratorINS_10FingerListENS_6FingerEEdeEv]+0x20): undefined reference to `Leap::FingerList::operator[](int) const'
/tmp/cc9HTgYi.o: In function `Leap::Frame::~Frame()':
Prueba1.cpp:(.text._ZN4Leap5FrameD2Ev[_ZN4Leap5FrameD5Ev]+0x16): undefined reference to `Leap::Interface::~Interface()'
/tmp/cc9HTgYi.o: In function `Leap::HandList::~HandList()':
Prueba1.cpp:(.text._ZN4Leap8HandListD2Ev[_ZN4Leap8HandListD5Ev]+0x16): undefined reference to `Leap::Interface::~Interface()'
/tmp/cc9HTgYi.o: In function `Leap::FingerList::~FingerList()':
Prueba1.cpp:(.text._ZN4Leap10FingerListD2Ev[_ZN4Leap10FingerListD5Ev]+0x16): undefined reference to `Leap::Interface::~Interface()'
/tmp/cc9HTgYi.o: In function `Leap::Hand::~Hand()':
Prueba1.cpp:(.text._ZN4Leap4HandD2Ev[_ZN4Leap4HandD5Ev]+0x16): undefined reference to `Leap::Interface::~Interface()'
/tmp/cc9HTgYi.o: In function `Leap::Bone::~Bone()':
Prueba1.cpp:(.text._ZN4Leap4BoneD2Ev[_ZN4Leap4BoneD5Ev]+0x16): undefined reference to `Leap::Interface::~Interface()'
/tmp/cc9HTgYi.o:(.rodata._ZTIN4Leap5FrameE[_ZTIN4Leap5FrameE]+0x8): undefined reference to `typeinfo for Leap::Interface'
/tmp/cc9HTgYi.o:(.rodata._ZTIN4Leap8HandListE[_ZTIN4Leap8HandListE]+0x8): undefined reference to `typeinfo for Leap::Interface'
/tmp/cc9HTgYi.o:(.rodata._ZTIN4Leap10FingerListE[_ZTIN4Leap10FingerListE]+0x8): undefined reference to `typeinfo for Leap::Interface'
/tmp/cc9HTgYi.o:(.rodata._ZTIN4Leap4HandE[_ZTIN4Leap4HandE]+0x8): undefined reference to `typeinfo for Leap::Interface'
/tmp/cc9HTgYi.o:(.rodata._ZTIN4Leap4BoneE[_ZTIN4Leap4BoneE]+0x8): undefined reference to `typeinfo for Leap::Interface'
/tmp/cc9HTgYi.o:(.rodata._ZTIN4Leap9PointableE[_ZTIN4Leap9PointableE]+0x8): more undefined references to `typeinfo for Leap::Interface' follow
collect2: error: ld returned 1 exit status
make: *** [Prueba1] Error 1

我的#include是：

#include <iostream>
#include <cstring>
#include "Leap.h"

所以看来问题出在Leap.h标题上。在SDK中有一个Sample.cpp，我可以编译并运行得很好。我使用相同的makefile和相同的文件系统;我使用相同的#include而不是Sample.cpp，所以我将.cpp文件移动到Sample.cpp所在的同一文件夹中并尝试编译，我得到了错误。我不知道如何解决它，任何想法？这是makefile：

OS := $(shell uname)
ARCH := $(shell uname -m)
CXXFLAGS := -std=c++0x -std=c++0x

ifeq ($(OS), Linux)
  ifeq ($(ARCH), x86_64)
LEAP_LIBRARY := ../lib/x64/libLeap.so -Wl,-rpath,../lib/x64
  else
LEAP_LIBRARY := ../lib/x86/libLeap.so -Wl,-rpath,../lib/x86
  endif
else
  # OS X
LEAP_LIBRARY := ../lib/libLeap.dylib
endif

Sample: Sample.cpp
$(CXX) -Wall  -g -I../include Sample.cpp -o Sample $(LEAP_LIBRARY)

ifeq ($(OS), Darwin)
install_name_tool -change @loader_path/libLeap.dylib ../lib/libLeap.dylib Sample
endif

clean:
rm -rf Sample Sample.dSYM

我只添加了CXXFLAGS来解决C + 98编译器错误。我也可以这样编译Sample.cpp，但是当我尝试在我的文件上执行相同操作时，我得到了错误。谢谢你的帮助！

Answer 1

所以看来问题出在Leap.h标题上。

不，标题没问题。您只是没有链接到提供这些函数定义的库。

查看makefile如何构建示例程序：它链接到libleap.so，

您需要这样做：

g++ -std=c++0x -std=c++0x    Prueba1.cpp   -o Prueba1 ../lib/x64/libleap.so -Wl,-rpath,../lib/x64

（如果您使用的是32位系统，则用x86替换x64。）

Answer 2

首先，必读：What is an undefined reference/unresolved external symbol error and how do I fix it?请至少阅读与外部库组件相关的答案，然后返回此问题。

好的，在您的情况下，您正在运行链接命令而不指定外部库。怎么会？为什么你能够编译包附带的样本？

看看makefile。它说

Sample: Sample.cpp
    $(CXX) -Wall  -g -I../include Sample.cpp -o Sample $(LEAP_LIBRARY)

这个规则告诉make三件事：要构建的（冒号前的第一行），构建它的内容来自（冒号后）和构建它（第二行）。所以当你运行像

这样的命令时

make Sample

make非常清楚该怎么做。

现在，如果你说

make Prueba1

事情有点不同。 makefile中没有关于Prueba1的特殊规则，因此make获取其（巨大的）内置规则集并查找允许其构建Prueba1的规则您。确实存在这样的内置规则，但它并不了解libLeap.so。这就是您在构建日志中看不到它的原因。

当然你可以在你的makefile中添加这样的东西：

Prueba1: Prueba1.cpp
    $(CXX) -Wall  -g -I../include Prueba1.cpp -o Prueba1 $(LEAP_LIBRARY)

但我冒昧地猜测，当你到达Prueba99时它会变得有点老。我们可以做得更好吗？

是的，我们可以，但让我们先回答另一个问题。你的编译命令怎么知道-std=c++0x？

这是因为您将此标记添加到内置宏 CXXFLAGS，并且内置规则使用此宏。顺便说一下，您不需要指定-std=c++0x两次。

有没有办法像编译器标志一样处理库？绝对！内置宏LDLIBS和LDFLAGS有两个。如果你这样定义它们：

LDLIBS := ../lib/x64/libLeap.so
LDFLAGS := -Wl,-rpath,../lib/x64

或（或者）

LDLIBS := -lLeap
LDFLAGS := -L ../lib/x64 -Wl,-rpath,../lib/x64

你的makefile应该能够针对libLeap构建任何C ++程序（如果它是作为单个C ++源文件编写的）。

将-I../include添加到CPPFLAGS可能是明智的，因为Sample规则使用它。您的编辑似乎没有它，但如果您编译，它可能会失败，例如更改您的工作目录。

g ++编译时未定义的引用错误

2 个答案: