Linux C++ 共享库未定义对 `FooClass::SayHello()' 的引用
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C++ shared library undefined reference to `FooClass::SayHello()'
提问by fivunlm
I'm making a C++ Shared Library and when I compile a main exe that uses the library the compiler gives me:
我正在制作一个 C++ 共享库，当我编译一个使用该库的主 exe 时，编译器给了我：
main.cpp:(.text+0x21): undefined reference to `FooClass::SayHello()'
collect2: ld returned 1 exit status
Library code:
图书馆代码：
fooclass.h
fooclass.h
#ifndef __FOOCLASS_H__
#define __FOOCLASS_H__
class FooClass
{
public:
char* SayHello();
};
#endif //__FOOCLASS_H__
fooclass.cpp
fooclass.cpp
#include "fooclass.h"
char* FooClass::SayHello()
{
return "Hello Im a Linux Shared Library";
}
Compiling with:
编译：
g++ -shared -fPIC fooclass.cpp -o libfoo.so
Main: main.cpp
主：main.cpp
#include "fooclass.h"
#include <iostream>
using namespace std;
int main(int argc, char const *argv[])
{
FooClass * fooClass = new FooClass();
cout<< fooClass->SayHello() << endl;
return 0;
}
Compiling with:
编译：
g++ -I. -L. -lfoo main.cpp -o main
The machine is an Ubuntu Linux 12
该机器是 Ubuntu Linux 12
Thanks!
谢谢！
采纳答案by fivunlm
g++ -I. -L. -lfoo main.cpp -o main
is the problem. Recent versions of GCC require that you put the object files and libraries in the order that they depend on each other - as a consequential rule of thumb, you have to put the library flags as the last switch for the linker; i. e., write
是问题所在。最新版本的 GCC 要求您按照相互依赖的顺序放置目标文件和库——根据经验法则，您必须将库标志作为链接器的最后一个开关；即，写
g++ -I. -L. main.cpp -o main -lfoo
instead.
反而。
