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I am trying to use curl inside c++ code. How should i do it properly ?

I have pasted libcurl.a & libcurl.dll.a in this directory: C:\Program Files\mingw-w64\x86_64-8.1.0-posix-seh-rt_v6-rev0\mingw64\lib

This is my CMakeLists.txt from CLion/Mingw

cmake_minimum_required(VERSION 3.3) 
project(tan)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++14 -lcurl.dll")
add_executable(tan Tan/mail.cpp)
project(untitled6)

When I add "#define CURL_STATICLIB" i get these errors:

reference to `curl_easy_init'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:84: undefined  
reference to `curl_easy_setopt'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:86: undefined reference to `curl_easy_setopt'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:91: undefined reference to `curl_slist_append'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:92: undefined reference to `curl_slist_append'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:93: undefined reference to `curl_easy_setopt'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:98: undefined reference to `curl_easy_setopt'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:99: undefined reference to `curl_easy_setopt'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:100: undefined reference to `curl_easy_setopt'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:103: undefined reference to `curl_easy_perform'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:107: undefined reference to `curl_easy_strerror'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:111: undefined reference to `curl_slist_free_all'
C:/Users/John/CLionProjects/tan/Tam/mail.cpp:121: undefined reference to ````curl_easy_cleanup

Without "#define CURL_STATICLIB" i get these errors:

CMakeFiles\tan.dir/objects.a(mail.cpp.obj): In function `main':
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:81: undefined reference to `__imp_curl_easy_init'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:84: undefined reference to `__imp_curl_easy_setopt'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:86: undefined reference to `__imp_curl_easy_setopt'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:91: undefined reference to `__imp_curl_slist_append'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:92: undefined reference to `__imp_curl_slist_append'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:93: undefined reference to `__imp_curl_easy_setopt'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:98: undefined reference to `__imp_curl_easy_setopt'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:99: undefined reference to `__imp_curl_easy_setopt'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:100: undefined reference to `__imp_curl_easy_setopt'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:103: undefined reference to `__imp_curl_easy_perform'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:107: undefined reference to `__imp_curl_easy_strerror'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:111: undefined reference to `__imp_curl_slist_free_all'
C:/Users/John/CLionProjects/tan/Tan/mail.cpp:121: undefined reference to `__imp_curl_easy_cleanup'
Galik
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John Byron
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    `-lcurl.dll` -- DLL's are not used in the build process -- they only come into play when your program is running. So why in your command-line are you specifying a DLL? – PaulMcKenzie May 26 '19 at 03:57
  • The linker flag should just be `-lcurl` . – Galik May 26 '19 at 03:58
  • Even with `-lcurl` I an getting same errors. I saw it in other post on StackOverflow. Thats why I added it thinking that might solve the problem. – John Byron May 26 '19 at 03:58

1 Answers1

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If anybody comes looking use this in CMakeLists.txt. The last line solved the issue.

Step1: Copy libcurl.dll.a in C:/curl. No need to copy "libcurl.a" OR "libcurl.dll.a" at any other place. No need for #define CURL_STATICLIB in main.cpp file

Step2: Edit the CMakeLists.txt as below. 

set(CMAKE_CXX_STANDARD 14)                                     
add_executable(tan Tan/mail.cpp)
project(untitled6)
target_link_libraries(tan "C:/curl/libcurl.dll.a")

Step3: If your program flashes quickly and closes. You might be missing some dll files. To check which ones you are missing , run the program (in my case tan.exe) with cmd. Take that dll from curl package (in my case curl-7.65.0-win64-mingw) and put it along side of your executable file. Make sure curl and your executable is compiled with same compiler. In my case it's Mingw.

John Byron
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