最近因项目需要使用qt做开发，之前使用LoadLibrary加载dll成功，很庆幸，当一切都那么顺风顺水的时候，测试同事却发现，在windows平台上个别电脑上加载dll会失败。现在加载返回空指针，强大的qt提供了QLibrary类，方便dll动态加载。
DWORD iErrorCode;
HINSTANCE hlib=LoadLibrary(TEXT("CartDll.dll"));
if(!hlib)
{
iErrorCode = GetLastError();
cout<<" last error code = "<<iErrorCode<<endl;
cout<<"open cart dll error!"<<endl;
return -1;
}
在Qt中使用LoadLibrary无法加载DLL
1.首先想到的是CartDll.dll相关依赖库缺失，查找dll依赖文件的方法
使用visual studio自带的工具查找
进入CartDll.dll所在目录，
输入命令：dumpbin -imports CartDll.dll
或者使用从定向到txt文本中：dumpbin -imports CartDll.dll > result.txt
Microsoft (R) COFF/PE Dumper Version 14.29.30138.0
Copyright (C) Microsoft Corporation. All rights reserved.
Dump of file CartDll.dll
File Type: DLL
Section contains the following imports:
libifcoremd.dll
1800AE0C8 Import Address Table
1800BBCF0 Import Name Table
0 time date stamp
0 Index of first forwarder reference
176 for_inquire
249 for_rewind
282 for_write_int_fmt_xmit
281 for_write_int_fmt
12B for_dealloc_allocatable
289 for_write_seq_lis_xmit
D2 for_concat
278 for_trim
248 for_read_seq_xmit
242 for_read_seq
DD for_cpystr
D1 for_close
1B2 for_pause
246 for_read_seq_lis_xmit
288 for_write_seq_lis
245 for_read_seq_lis
1B1 for_open
179 for_is_nan_s_
26F for_stop_core
287 for_write_seq_fmt_xmit
286 for_write_seq_fmt
libifportMD.dll
1800AE178 Import Address Table
1800BBDA0 Import Name Table
0 time date stamp
0 Index of first forwarder reference
154 SYSTEM
libmmd.dll
1800AE188 Import Address Table
1800BBDB0 Import Name Table
0 time date stamp
0 Index of first forwarder reference
1D8 cbrtf
336 sinf
2E2 logf
345 tanf
153 __libm_sse2_sincos
1EE cexpf
20B cos
20F cosf
173 __powr4i4
2D7 log10f
30C powf
154 __libm_sse2_sincosf
246 expf
19C acosf
MSVCR110.dll
1800AE040 Import Address Table
1800BBC68 Import Name Table
0 time date stamp
0 Index of first forwarder reference
336 _lock
49B _unlock
5EB memmove
18D __dllonexit
3DD _onexit
17E __clean_type_info_names_internal
161 __CppXcptFilter
1E0 _amsg_exit
5A3 free
347 _malloc_crt
2C6 _initterm
2C7 _initterm_e
1F6 _calloc_crt
5E9 memcpy
5ED memset
160 __C_specific_handler
svml_dispmd.dll
1800AE200 Import Address Table
1800BBE28 Import Name Table
0 time date stamp
0 Index of first forwarder reference
392 __svml_logf4
399 __svml_logf4_mask
3BB __svml_powf4_mask
3B6 __svml_powf4
316 __svml_irem4
482 __svml_tanf4
286 __svml_expf4
10 __svml_acosf4
1AE __svml_cosf4
28B __svml_expf4_mask
KERNEL32.dll
1800AE000 Import Address Table
1800BBC28 Import Name Table
0 time date stamp
0 Index of first forwarder reference
318 GetTickCount64
2FB GetSystemTimeAsFileTime
22E GetCurrentThreadId
43F QueryPerformanceCounter
118 DecodePointer
140 EncodePointer
132 DisableThreadLibraryCalls
Summary
193FE000 .data
3000 .pdata
F000 .rdata
3000 .reloc
1000 .rsrc
AD000 .text
2.方法二使用Dependencies.exe工具打开 CartDll.dll
3.方法3：修改代码
int main()
{
DWORD iErrorCode;
// HINSTANCE hlib=LoadLibrary(TEXT("CartDll.dll"));
// QString strFilePath = "CartDll.dll";
LPCWSTR lpLibFileName = TEXT("E:\\osg\\work\\CallCartDll_20230721\\CallCartDll\\CartDll.dll");
HINSTANCE hlib= LoadLibraryEx(lpLibFileName,NULL,LOAD_WITH_ALTERED_SEARCH_PATH);
if(!hlib)
{
iErrorCode = GetLastError();
cout<<" last error code = "<<iErrorCode<<endl;
cout<<"open cart dll error!"<<endl;
return -1;
}
}