我在尝试使用第三方SDK和在XP上使用eclipse编写的C ++程序时遇到上述错误。根据搜索，我了解此错误是由链接器未正确指向.dll或.lib引起的。我已经在环境变量 - PATH中包含了这些项的路径，也在Properties \ C / C ++ Build \ Settings \ MinGW C ++ Linker \ Libraries中的eclipse中包含了这些项的路径。用于这两个项目的路径是C：\ Program Files \ Card Scanning Solutions \ SDK
这是控制台输出：
**** Build of configuration Debug for project HelloWorld ****
**** Internal Builder is used for build ****
g++ -IC:\Program Files\Card Scanning Solutions\SDK -O0 -g3 -Wall -c -fmessage-length=0 -lm -v -o src\BizScan.o ..\src\BizScan.cpp
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=c:/mingw/bin/../libexec/gcc/mingw32/4.6.1/lto-wrapper.exe
Target: mingw32
Configured with: ../gcc-4.6.1/configure --enable-languages=c,c++,fortran,objc,obj-c++ --disable-sjlj-exceptions --with-dwarf2 --enable-shared --enable-libgomp --disable-win32-registry --enable-libstdcxx-debug --enable-version-specific-runtime-libs --build=mingw32 --prefix=/mingw
Thread model: win32
gcc version 4.6.1 (GCC)
COLLECT_GCC_OPTIONS='-I' 'C:\Program Files\Card Scanning Solutions\SDK' '-O0' '-g3' '-Wall' '-c' '-fmessage-length=0' '-v' '-o' 'src\BizScan.o' '-shared-libgcc' '-mtune=i386' '-march=i386'
c:/mingw/bin/../libexec/gcc/mingw32/4.6.1/cc1plus.exe -quiet -v -I C:\Program Files\Card Scanning Solutions\SDK -iprefix c:\mingw\bin\../lib/gcc/mingw32/4.6.1/ -dD ..\src\BizScan.cpp -quiet -dumpbase BizScan.cpp -mtune=i386 -march=i386 -auxbase-strip src\BizScan.o -g3 -O0 -Wall -version -fmessage-length=0 -o C:\DOCUME~1\Game\LOCALS~1\Temp\ccwufpbm.s
GNU C++ (GCC) version 4.6.1 (mingw32)
compiled by GNU C version 4.6.1, GMP version 5.0.1, MPFR version 2.4.1, MPC version 0.8.1
GGC heuristics: --param ggc-min-expand=64 --param ggc-min-heapsize=65307
ignoring nonexistent directory "c:\mingw\bin\../lib/gcc/mingw32/4.6.1/../../../../mingw32/include"
ignoring duplicate directory "c:/mingw/lib/gcc/../../lib/gcc/mingw32/4.6.1/include/c++"
ignoring duplicate directory "c:/mingw/lib/gcc/../../lib/gcc/mingw32/4.6.1/include/c++/mingw32"
ignoring duplicate directory "c:/mingw/lib/gcc/../../lib/gcc/mingw32/4.6.1/include/c++/backward"
ignoring duplicate directory "c:/mingw/lib/gcc/../../lib/gcc/mingw32/4.6.1/include"
ignoring duplicate directory "/mingw/lib/gcc/mingw32/4.6.1/../../../../include"
ignoring duplicate directory "c:/mingw/lib/gcc/../../include"
ignoring duplicate directory "c:/mingw/lib/gcc/../../lib/gcc/mingw32/4.6.1/include-fixed"
ignoring nonexistent directory "c:/mingw/lib/gcc/../../lib/gcc/mingw32/4.6.1/../../../../mingw32/include"
ignoring duplicate directory "/mingw/include"
#include "..." search starts here:
#include <...> search starts here:
C:\Program Files\Card Scanning Solutions\SDK
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/mingw32
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include/c++/backward
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/../../../../include
c:\mingw\bin\../lib/gcc/mingw32/4.6.1/include-fixed
End of search list.
GNU C++ (GCC) version 4.6.1 (mingw32)
compiled by GNU C version 4.6.1, GMP version 5.0.1, MPFR version 2.4.1, MPC version 0.8.1
GGC heuristics: --param ggc-min-expand=64 --param ggc-min-heapsize=65307
Compiler executable checksum: 8e56a7b4b7f3db333ff95dd4b2d788a4
COLLECT_GCC_OPTIONS='-I' 'C:\Program Files\Card Scanning Solutions\SDK' '-O0' '-g3' '-Wall' '-c' '-fmessage-length=0' '-v' '-o' 'src\BizScan.o' '-shared-libgcc' '-mtune=i386' '-march=i386'
c:/mingw/bin/../lib/gcc/mingw32/4.6.1/../../../../mingw32/bin/as.exe -o src\BizScan.o C:\DOCUME~1\Game\LOCALS~1\Temp\ccwufpbm.s
COMPILER_PATH=c:/mingw/bin/../libexec/gcc/mingw32/4.6.1/;c:/mingw/bin/../libexec/gcc/;c:/mingw/bin/../lib/gcc/mingw32/4.6.1/../../../../mingw32/bin/
LIBRARY_PATH=c:/mingw/bin/../lib/gcc/mingw32/4.6.1/;c:/mingw/bin/../lib/gcc/;c:/mingw/bin/../lib/gcc/mingw32/4.6.1/../../../../mingw32/lib/;c:/mingw/bin/../lib/gcc/mingw32/4.6.1/../../../;/mingw/lib/
COLLECT_GCC_OPTIONS='-I' 'C:\Program Files\Card Scanning Solutions\SDK' '-O0' '-g3' '-Wall' '-c' '-fmessage-length=0' '-v' '-o' 'src\BizScan.o' '-shared-libgcc' '-mtune=i386' '-march=i386'
g++ -LC:\Program Files\Card Scanning Solutions\SDK -lm -o HelloWorld.exe src\HelloWorld.o src\BizScan.o
src\BizScan.o: In function `ZN7BizScan4InitEv':
C:\Documents and Settings\Game\workspace\HelloWorld\Debug/../src/BizScan.cpp:20: undefined reference to `_imp__UseFixedModel'
C:\Documents and Settings\Game\workspace\HelloWorld\Debug/../src/BizScan.cpp:22: undefined reference to `_imp__SetTwainScanner'
C:\Documents and Settings\Game\workspace\HelloWorld\Debug/../src/BizScan.cpp:23: undefined reference to `_imp__InitScanLib'
C:\Documents and Settings\Game\workspace\HelloWorld\Debug/../src/BizScan.cpp:27: undefined reference to `_imp__InitImageLib'
C:\Documents and Settings\Game\workspace\HelloWorld\Debug/../src/BizScan.cpp:31: undefined reference to `_imp__InitBizLib'
src\BizScan.o: In function `~BizScan':
C:\Documents and Settings\Game\workspace\HelloWorld\Debug/../src/BizScan.cpp:39: undefined reference to `_imp__UnInitScanLib'
collect2: ld returned 1 exit status
Build error occurred, build is stopped
Time consumed: 5648 ms.
这是BizScan.cpp：
/*
* BizScan.cpp
*
* Created on: Feb 13, 2012
* Author: TFB
*/
#include "BizScan.h"
#include "slibexp.h" // ScanLib SDK header file
#include "..\header_lib\BizExp.h" // ScanLib SDK header file
#include "..\header_lib\ImageExp.h" // ScanLib SDK header file
#include "CSSN.h"
#include "windef.h"
BizScan::BizScan() {
BizScan::Init();
}
const char* BizScan::Init() {
UseFixedModel(11);
const char *scannerSelected = "WIA-A6 Scanner 735";
int result = SetTwainScanner(scannerSelected);
result = InitScanLib(CSSN::GetSDKLicense().c_str());
if(result < 0 && result != -13){
return ScannerErrors(result);
} else {
result = InitImageLib(CSSN::GetSDKLicense().c_str());//initialize Image Lib SDK
if(result < 0 && result != -13)//if error
return ImageErrors(result);//call image lib sdk
result = InitBizLib(CSSN::GetSDKLicense().c_str());//initialize Biz Card Lib Scanner SDK
if(result < 0 && result != -13)//if error
return BizErrors(result);//call biz card scanner Lib SDK error handler
}
return "Successful Initialization !!";
}
BizScan::~BizScan() {
UnInitScanLib();
}
这是BizScan.h：
/*
* BizScan.h
*
* Created on: Feb 13, 2012
* Author: TFB
*/
#ifndef BIZSCAN_H_
#define BIZSCAN_H_
#include "windef.h"
typedef HINSTANCE hDLL;
class BizScan {
private:
public:
BizScan();
virtual ~BizScan();
const char* Init() ;
};
#endif /* BIZSCAN_H_ */
这是slibexp.h的相关部分：
/*/////////////////////////////////////////////////////////////////////
//
// SLibExp.h
//
// Card Scanning Solutions (LLC)
// All Rights Reserved
//
/////////////////////////////////////////////////////////////////////*/
#ifndef SLIBEXP_H
#define SLIBEXP_H
#ifdef SDLL
#define SDLL_EXP __declspec( dllexport )
#else
#define SDLL_EXP __declspec( dllimport )
#endif
// Functions Prototypes
#if defined __cplusplus || defined c_plusplus
extern "C"
{
#endif
SDLL_EXP void UseFixedModel(int val);
SDLL_EXP short SetTwainScanner(const char *szStr);
SDLL_EXP short InitScanLib(const char * license);
IMAGE_EXPORT short InitImageLib(const char *licanse);
SDLL_EXP short UnInitScanLib();
#if defined __cplusplus || defined c_plusplus
};
#endif
#endif /* SLIBEXP_H */
控制台输出中引用的其他两个方法都在同一文件夹（项目根目录）中的其他头文件中定义。这些定义如下：
IMAGE_EXPORT short InitImageLib(const char *licanse);
extern "C" BIZ_EXPORT short InitBizLib(const char *license);
还有其他地方我需要链接这些.dll的。我尝试使用LoadLibrary（）方法，但该方法因不属于范围而被拒绝。我该如何链接到这些dll？感谢您提出的任何指示。
答案 0 :(得分：1)
查看您显示的输出，这是相关命令：
g++ -LC:\Program Files\Card Scanning Solutions\SDK -lm -o HelloWorld.exe src\HelloWorld.o src\BizScan.o
它包含库的路径，但实际的库本身没有引用。我不知道库的名称是什么，但我们假设它是libBizLib.a，在该命令的末尾应该有-lBizLib;或者如果你想链接到dll，你可以使用它的全名（没有-l）。
（顺便提一下，你提到了库的.lib扩展名。这通常表示一个Visual Studio库。你确定你的版本是否与MinGW兼容？）
答案 1 :(得分：1)
最近我也遇到了类似的问题。看来是由于编译器的不同。该库是使用MinGW w64的一个版本构建的，而我的版本则是如此不同，以至于我无法在该库随附的.a文件中进行编译。
但是您可以在运行时使用LoadLibrary使用dll，但是在调用它时必须更加明确。那么，dll不会加载的主要方式是文件不在dll加载路径中，或者dll是错误的位类型（32位v 64位）。
希望有帮助。