我試圖構建一個可用於與兩個動態和靜態鏈接的靜態和動態庫。我希望無論使用何種編譯器,庫都可以在儘可能多的平臺上運行。爲了構建庫和一些測試程序,我使用CMake在Linux和Windows上分別使用g ++和MSVC++構建庫eeg。
在Linux上,動態庫和靜態庫看起來都像我懷疑的那樣工作,在Windows上.dll似乎完美鏈接,我的測試程序運行。但是,使用靜態庫的程序會抱怨鏈接錯誤。我真的很想念我做錯了什麼,它可能是我的CMakeLists.txt中的東西,也可能是我的庫的設置。 下面我做了一個最小化的程序,它使用我的庫來演示我遇到的問題。該庫包含兩個C++文件,一個用於導出C++文件中代碼的C API,一個使用C API的C++程序以及一個可以構建除使用靜態庫的程序之外的所有程序的CMakeList.txt。這一切產生了一個奇妙的「你好,世界!」。
我知道我展示了很多代碼,但至少它是一個最小的項目,它演示了我的鏈接到靜態庫的問題。我希望有人善意地看看這個項目,並向我解釋我做錯了什麼。
此致
hetepeperfan
的C++文件PriCpp.cpp
#include "PriCpp.h"
using namespace std;
string PriMessageBuilder::message() const {
return "Hello, World!";
}
頭PriCpp.h
#ifndef PRICPP_H
#define PRICPP_H
#include <string>
class PriMessageBuilder{
public:
std::string message() const;
};
#endif
的C API是: mycapi.h
#ifndef MYCAPI_H
#define MYCAPI_H
#include "builder_export.h"
#ifdef __cplusplus
extern "C" {
#endif
typedef struct {} message_builder;
BUILDER_EXPORT message_builder* message_builder_new();
BUILDER_EXPORT void message_builder_destroy(
message_builder* builder
);
BUILDER_EXPORT char* message_builder_message(
message_builder* builder
);
#ifdef __cplusplus
}
#endif
#endif
mycapi.cpp是:
#include "mycapi.h"
#include "PriCpp.h"
#include <cstring>
#include <cstdlib>
message_builder* message_builder_new() {
PriMessageBuilder* ret = NULL;
try {
ret = new PriMessageBuilder();
} catch (...) {
}
return reinterpret_cast<message_builder*>(ret);
}
void message_builder_destroy(message_builder* builder)
{
PriMessageBuilder* b = reinterpret_cast<PriMessageBuilder*>(builder);
delete b;
}
char* message_builder_message(message_builder* builder)
{
PriMessageBuilder* b = reinterpret_cast<PriMessageBuilder*>(builder);
return strdup(b->message().c_str());
}
,我結合使用與上面的庫中的程序。 program.cpp
#include <iostream>
#include <cstdlib>
#include <string>
#include "mycapi.h"
using namespace std;
class MessageBuilder {
public:
MessageBuilder() : m_builder(message_builder_new()) {
}
~MessageBuilder() {
message_builder_destroy(m_builder);
}
string MessageBuilder::message() {
char* msg = message_builder_message(m_builder);
string m(msg);
free (msg);
return m;
}
private:
message_builder* m_builder;
};
int main(int, char**) {
MessageBuilder m;
cout << m.message() << endl;
return 0;
}
最後的CMakeLists.txt建立一個makefile文件或Visual Studio解決方案
#setting up project
cmake_minimum_required(VERSION 2.6)
project(libbuilder CXX)
include (GenerateExportHeader)
include_directories("${PROJECT_BINARY_DIR}")
#creating library
add_library(builder SHARED PriCpp.cpp PriCpp.h mycapi.cpp mycapi.h)
add_library(builder-static STATIC PriCpp.cpp PriCpp.h mycapi.cpp mycapi.h)
generate_export_header(builder)
set_target_properties(builder PROPERTIES COMPILE_FLAGS -DBUILD_BUILDER_SHARED)
set_target_properties(builder-static PROPERTIES COMPILE_FLAGS -DBUILDER_STATIC_DEFINE)
#creating programs
add_executable(program program.cpp)
add_executable(program-static program.cpp)
target_link_libraries(program builder)
target_link_libraries(program-static builder-static)
如果我構建解決方案我得到這些鏈接器錯誤:
1>program.obj : error LNK2019: unresolved external symbol __imp__message_builder_new referenced in function "public: __thiscall MessageBuilder::MessageBuilder(void)" ([email protected]@[email protected])
1>program.obj : error LNK2019: unresolved external symbol __imp__message_builder_destroy referenced in function "public: __thiscall MessageBuilder::~MessageBuilder(void)" ([email protected]@[email protected])
1>program.obj : error LNK2019: unresolved external symbol __imp__message_builder_message referenced in function "public: class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __thiscall MessageBuilder::message(void)" ([email protected]@@[email protected][email protected]@[email protected]@[email protected]@[email protected]@[email protected]@XZ)
1>K:\duijn119\programming\cmake\staticsharedlib\build\Debug\program-static.exe : fatal error LNK1120: 3 unresolved externals
CMake生成的包含標頭爲:
#ifndef BUILDER_EXPORT_H
#define BUILDER_EXPORT_H
#ifdef BUILDER_STATIC_DEFINE
# define BUILDER_EXPORT
# define BUILDER_NO_EXPORT
#else
# ifndef BUILDER_EXPORT
# ifdef builder_EXPORTS
/* We are building this library */
# define BUILDER_EXPORT __declspec(dllexport)
# else
/* We are using this library */
# define BUILDER_EXPORT __declspec(dllimport)
# endif
# endif
# ifndef BUILDER_NO_EXPORT
# define BUILDER_NO_EXPORT
# endif
#endif
#ifndef BUILDER_DEPRECATED
# define BUILDER_DEPRECATED __declspec(deprecated)
#endif
#ifndef BUILDER_DEPRECATED_EXPORT
# define BUILDER_DEPRECATED_EXPORT BUILDER_EXPORT BUILDER_DEPRECATED
#endif
#ifndef BUILDER_DEPRECATED_NO_EXPORT
# define BUILDER_DEPRECATED_NO_EXPORT BUILDER_NO_EXPORT BUILDER_DEPRECATED
#endif
#define DEFINE_NO_DEPRECATED 0
#if DEFINE_NO_DEPRECATED
# define BUILDER_NO_DEPRECATED
#endif
#endif
不能確定,但你真的需要'的extern 「C」'在頭,因爲你有C++實現? – dmi
@dmi是的我很確定我需要extern「C」。我想使用C調用約定,所以沒有名稱調整。這樣可以更輕鬆地從C程序中調用庫中的函數。 C API還通過dll邊界隱藏了標準C++庫中的類。這保持了不同C/C++編譯器之間的ABI穩定性。 – hetepeperfan
如果刪除所有非靜態庫和可執行文件,問題依然存在嗎?如果是這樣,請在沒有它們的情況下發布'CMakeLists.txt'。 – Tsyvarev