[C/C++] 在 Windows 上 Build static libCURL library

libcurl 是個跨平台的 library ，支援非常多的 protocol，重點還是 open source!
以下就是簡單的 build 出一個 libcurl 的 static library 教學

1. 首先 download libcurl 的 source code 壓縮檔

libCURL download page

2. 在 command line 準備好 VC 的 compile 環境

"{VC Install Path}\VC\vcvarsall.bat" x86

設置完環境後，才能執行 namke

3. 開始 build libcurl

cd {libcurl extract dir}\winbuild
nmake /f Makefile.vc mode=static DEBUG=yes MAXHINE=x86

mode = static 也可以是 dll ，只是我們目標是 static library
build 完後，可以在 {libcurl extract dir}\builds 找到 lib 還有 header 檔

其他參數說明

• VC=<6,7,8,9,10>
• VC版本(不一定要填)
• WITH_SSL=<dll or static>
• 使用OpenSSL詳細參閱，會有 License 問題
• ENABLE_WINSSL=<yes or no>
• Enable native 的 Windows SSL 功能
• 記得，如果要 enable 的話，ENABLE_SSPI一定也要 enable !
• GEN_PDB=<yes or no>
• 產生 .pdb 檔
• DEBUG=<yes or no>
• Debug or Release mode
• MACHINE=<x86 or x64>
• Target architecture
• RTLIBCFG
• 不指定就是 default，compile 參數會加上 /MD or /MDd (Multi-threaded)
• =static，compile 參數會加上 /MT or /MTd (Multi-threaded DLL)

4. VC project setting 設置

在 Project Property | Linker | General | Additional Library Directories 
加上放有 build 出的 .lib 的目錄

在 Project Property | Linker | Input | Additional Dependencies 
加上 libcurl_a.lib or libcurl_a_debug.lib

在 Project Property | C/C++ | Preprocessor 
加上 CURL_STATICLIB 這個 macro 才行
否則會出現類似這樣的錯誤訊息：

1>A.obj : error LNK2019: unresolved external symbol __imp__curl_global_init referenced in function "bool __cdecl DownloadProtectedKey(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?DownloadProtectedKey@@YA_NAAV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V12@11@Z)
1>A.obj : error LNK2019: unresolved external symbol __imp__curl_slist_append referenced in function "bool __cdecl DownloadProtectedKey(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?DownloadProtectedKey@@YA_NAAV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V12@11@Z)
1>A.obj : error LNK2019: unresolved external symbol __imp__curl_slist_free_all referenced in function "bool __cdecl DownloadProtectedKey(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?DownloadProtectedKey@@YA_NAAV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V12@11@Z)
1>A.obj : error LNK2019: unresolved external symbol __imp__curl_easy_strerror referenced in function "bool __cdecl DownloadProtectedKey(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?DownloadProtectedKey@@YA_NAAV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V12@11@Z)
1>A.obj : error LNK2019: unresolved external symbol __imp__curl_easy_init referenced in function "bool __cdecl DownloadProtectedKey(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?DownloadProtectedKey@@YA_NAAV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V12@11@Z)
1>A.obj : error LNK2019: unresolved external symbol __imp__curl_easy_setopt referenced in function "bool __cdecl DownloadProtectedKey(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?DownloadProtectedKey@@YA_NAAV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V12@11@Z)
1>A.obj : error LNK2019: unresolved external symbol __imp__curl_easy_perform referenced in function "bool __cdecl DownloadProtectedKey(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?DownloadProtectedKey@@YA_NAAV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V12@11@Z)
1>A.obj : error LNK2019: unresolved external symbol __imp__curl_easy_cleanup referenced in function "bool __cdecl DownloadProtectedKey(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?DownloadProtectedKey@@YA_NAAV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V12@11@Z)