使用静态库时对函数的引用未定义
我正在尝试写一个使用遗传算法的程序，这是一种特殊类型的优化算法。为此，我找到了一个免费的库"Evolutionary Objects“，并实现了一个非常简单的遗传算法实例。程序代码、netbeans实现的构建命令以及我收到的错误消息都在下面单独的块中发布。如果您允许我提供帮助，您会发现cout函数出了问题。当我在互联网上搜索类似的困难时，我发现人们已经通过简单地使用g++而不是gcc来纠正问题，而我已经在使用g++了，正如你所看到的。任何帮助都将不胜感激..。
程序代码紧跟在下面：
#include <stdexcept>
#include <iostream>
#include <eo>
#include <ga.h>
typedef eoBit<double> Indi;
double binary_value(const Indi & _indi)
{
double sum = 0;
for (unsigned i = 0; i < _indi.size(); i++)
sum += _indi[i];
return sum;
}
void main_function(int argc, char **argv)
{
const unsigned int SEED = 42; // seed for random number generator
const unsigned int T_SIZE = 3; // size for tournament selection
const unsigned int VEC_SIZE = 16; // Number of bits in genotypes
const unsigned int POP_SIZE = 100; // Size of population
const unsigned int MAX_GEN = 400; // Maximum number of generation before STOP
const float CROSS_RATE = 0.8; // Crossover rate
const double P_MUT_PER_BIT = 0.01; // probability of bit-flip mutation
const float MUT_RATE = 1.0; // mutation rate
rng.reseed(SEED);
eoEvalFuncPtr<Indi> eval( binary_value );
eoPop<Indi> pop;
for (unsigned int igeno=0; igeno<POP_SIZE; igeno++)
{
Indi v; // void individual, to be filled
for (unsigned ivar=0; ivar<VEC_SIZE; ivar++)
{
bool r = rng.flip(); // new value, random in {0,1}
v.push_back(r); // append that random value to v
}
eval(v); // evaluate it
pop.push_back(v); // and put it in the population
}
pop.sort();
cout << "Initial Population" << endl;
cout << pop;
eoDetTournamentSelect<Indi> select(T_SIZE); // T_SIZE in [2,POP_SIZE]
eo1PtBitXover<Indi> xover;
eoBitMutation<Indi> mutation(P_MUT_PER_BIT);
eoGenContinue<Indi> continuator(MAX_GEN);
eoSGA<Indi> gga(select, xover, CROSS_RATE, mutation, MUT_RATE, eval, continuator);
gga(pop);
pop.sort();
cout << "FINAL Population\n" << pop << endl;
}
int main(int argc, char **argv)
{
main_function(argc, argv);
return 1;
}
}Netbeans向我展示了它在尝试构建时正在做的事情：
make[1]: Entering directory `/home/gregemerson/EO_GA/EO_GA'
rm -f -r build/Debug
rm -f dist/Debug/GNU-Linux-x86/eo_ga
make[1]: Leaving directory `/home/gregemerson/EO_GA/EO_GA'
CLEAN SUCCESSFUL (total time: 94ms)
"/usr/bin/make" -f nbproject/Makefile-Debug.mk QMAKE= SUBPROJECTS= .build-conf
make[1]: Entering directory `/home/gregemerson/EO_GA/EO_GA'
"/usr/bin/make" -f nbproject/Makefile-Debug.mk dist/Debug/GNU-Linux-x86/eo_ga
make[2]: Entering directory `/home/gregemerson/EO_GA/EO_GA'
mkdir -p build/Debug/GNU-Linux-x86
rm -f build/Debug/GNU-Linux-x86/main.o.d
g++ -c -g -I../../EO/EO/eo/src -MMD -MP -MF build/Debug/GNU-Linux-x86/main.o.d -o build/Debug/GNU-Linux-x86/main.o main.cpp
mkdir -p dist/Debug/GNU-Linux-x86
g++ -o dist/Debug/GNU-Linux-x86/eo_ga build/Debug/GNU-Linux-x86/main.o -L../../EO/EO/eo/build/lib /home/gregemerson/EO/EO/eo/build/lib/libcma.a /home/gregemerson/EO/EO/eo/build/lib/libeoutils.a /home/gregemerson/EO/EO/eo/build/lib/libes.a /home/gregemerson/EO/EO/eo/build/lib/libga.a 错误消息紧跟在下面：
/home/gregemerson/EO_GA/EO_GA/main.cpp:94: undefined reference to `operator<<(std::basic_ostream<char, std::char_traits<char> >&, eoPrintable const&)'
/home/gregemerson/EO_GA/EO_GA/main.cpp:99: undefined reference to `operator<<(std::basic_ostream<char, std::char_traits<char> >&, eoPrintable const&)'
/home/gregemerson/EO_GA/EO_GA/main.cpp:149: undefined reference to `operator<<(std::basic_ostream<char, std::char_traits<char> >&, eoPrintable const&)'
build/Debug/GNU-Linux-x86/main.o: In function `eoPop<eoBit<double> >::sortedPrintOn(std::basic_ostream<char, std::char_traits<char> >&) const':
/home/gregemerson/EO_GA/EO_GA/../../EO/EO/eo/src/eoPop.h:294: undefined reference to `operator<<(std::basic_ostream<char, std::char_traits<char> >&, eoPrintable const&)'
build/Debug/GNU-Linux-x86/main.o: In function `std::ostream_iterator<eoBit<double>, char, std::char_traits<char> >::operator=(eoBit<double> const&)':
/usr/include/c++/4.6/bits/stream_iterator.h:198: undefined reference to `operator<<(std::basic_ostream<char, std::char_traits<char> >&, eoPrintable const&)'
collect2: ld returned 1 exit status
make[2]: *** [dist/Debug/GNU-Linux-x86/eo_ga] Error 1
make[2]: Leaving directory `/home/gregemerson/EO_GA/EO_GA'
make[1]: *** [.build-conf] Error 2
make[1]: Leaving directory `/home/gregemerson/EO_GA/EO_GA'
make: *** [.build-impl] Error 2您的回答确实纠正了我的cout(pop)问题。但是，我现在在我正在使用的一个静态库的头文件中看到了类似的错误，以及看起来与一个基本c++库相关的头文件。我得到了以下结论。这对你来说有意义吗？
build/Debug/GNU-Linux-x86/main.o: In function `std::ostream_iterator<eoBit<double>, char, std::char_traits<char> >::operator=(eoBit<double> const&)':
/usr/include/c++/4.6/bits/stream_iterator.h:198: undefined reference to `operator<<(std::basic_ostream<char, std::char_traits<char> >&, eoPrintable const&)'
build/Debug/GNU-Linux-x86/main.o: In function `eoPop<eoBit<double> >::sortedPrintOn(std::basic_ostream<char, std::char_traits<char> >&) const':
/home/gregemerson/EO_GA/EO_GA/../../EO/EO/eo/src/eoPop.h:294: undefined reference to `operator<<(std::basic_ostream<char, std::char_traits<char> >&, eoPrintable const&)'回答 2
Stack Overflow用户
发布于 2012-06-30 02:40:29
问题是(例如)这里：
cout << pop;错误，
/home/gregemerson/EO_GA/EO_GA/main.cpp:94: undefined reference to
`operator<<(std::basic_ostream<char, std::char_traits<char> >&, eoPrintable const&)'意味着没有知道如何将eoPrintable对象推入ostream的基本函数。
基于注释中提供的link，这个eoPop类定义了一些打印方法：sortedPrintOn和printOn。
为了使用其中一个打印到cout，您需要执行以下操作：
pop.printOn(cout); //or pop.printOn(std::cout) if you remove using namespace std;
pop.printSortedOn(cout);Stack Overflow用户
发布于 2015-06-02 17:20:26
许多人在第一次尝试使用EO C++库时都遇到了这个问题。我也遇到了这个问题，并找到了解决方案。问题是链接器在构建EO程序时找不到必须链接的静态库。我现在能够在Ubunut10.04 (LTS)上成功地编译和使用第一个教程，即FirstBitGA.cpp & FirstRealGA.cpp和EO-1.3.1。
注意：我正在编写从安装开始的完整步骤，请耐心等待。同时将“username”替换为您的用户帐户。
<< Solution >>
主目录从http://sourceforge.net/projects/eodev/files/latest/download?source=files
- Create下载EO，一个名为EO的目录；我在//
- /中创建它。
- 将EO Zip文件复制到/home/用户名/EO并解压缩。这将在terminal.
- The构建脚本中的/home/username/EO/eo / build _ /home/username/EO.
- Now _linux_release中运行构建脚本，在/home/用户名/eo/eo/eo下创建另一个名为'eo‘的目录。在step-4中的terminal.
- The构建脚本中，将在/home/用户名/eo/eo下创建一个名为'release’的目录。在发布目录中，'lib‘文件夹包含编译任何EO程序时必须链接的库。
- 现在必须向编译器提供两个路径才能成功编译：
6.1。将文件作为g++的命令行参数包含的路径，即-I /home/用户名/eo/eo/src < OR >如果您使用的是Qt creator IDE，则在probject的.pro文件中输入行‘INCLUDEPATH += /home/username/EO/eo/src’。
6.2。带有g++的-L参数的所有链接库的路径，即
-L/home/用户名/eo/release/lib/libcma.a/home/用户名/eo/eo/release/lib/libeo.a /home/username/EO/eo/release/lib/libeoserial/home/username/EO/eo/release/lib/libeoutils.a /home/用户名/eo/eo/release/lib/libes.a/home/用户名/eo/release/lib/libga.a
对于Qt Creator用户，在.pro文件中输入以下行：
/home/username/EO/eo/release/lib/libga.a
- Enjoy
+= -L/home/用户名/eo/eo/release/lib/libcma.a/home/用户名/eo/release/lib/libeo.a /home/username/EO/eo/release/lib/libeoserial.a /home/用户名/eo/eo/release/lib/libeoutils.a/home/用户名/eo/eo/release/lib/libes.a LIBS
https://stackoverflow.com/questions/11267073
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