在windows下，编译可访问https的libcurl静态库过程

1. 首先编译openssl静态库

整个过程用的是 vs2015命令提示工具

需要安装perl
下载地址：添加链接描述
解压后， 在 openssl-1.0.2e目录下创建develop这个文件夹， cd到 openssl-1.0.2e目录下，

a.配置编译文件和模式
执行

perl Configure VC-WIN32 no-asm --prefix=E:\curl\openssl-1.0.2e\develop

VC-WIN32标识windows 32位操作系统，
64位用VC-WIN64A表示， 若要使用debug版本，请使用debug-VC-WIN64A或debug-VC-WIN32
no-asm 表示不用汇编
–prefix=E:\curl\openssl-1.0.2e\develop 是设置安装目录
b.生成编译配置文件
若为Windows 64位系统，执行

ms\do_win64a.bat

若为Windows 32位系统，执行

ms\do_ms.bat

执行这一步之后，在ms目录下会生成nt.mak和ntdll.mak两个编译配置文件
nt.mak 用于生成静态lib库
ntdll.mak 用于生成动态dll库
c.编译
静态库

nmake -f ms\nt.mak	

动态库

nmake -f ms\ntdll.mak

d.测试
测试静态库：

 nmake -f ms\nt.mak test

测试动态库：

 nmake -f ms\ntdll.mak test

若最终显示 passed all tests 则说明生成的库正确
e.安装
安装静态库：

nmake -f ms\nt.mak install

安装动态库：

nmake -f ms\ntdll.mak install

编译安装完成后，会在E:\curl\openssl-1.0.2e\develop目录下看到生成的相关文件夹
f.清楚上次编译
清除上次静态库的编译，以便重新编译：

nmake -f ms\nt.mak clean

清除上次动态库的编译，以便重新编译：

nmake -f ms\ntdll.mak clean

参考：https://blog.youkuaiyun.com/mayue_web/article/details/83997969，非常详细

2.编译zlib

a.下载源码
http://zlib.net/zlib-1.2.11.tar.gz
解压后，在zlib根目录下 命令行执行
nmake -f win32/Makefile.msc

3.编译libcurl

a.下载源码
http://curl.haxx.se/download/curl-7.46.0.tar.bz2
b.拷贝所需的openssl与zlib相关库与头文件
.根据curl源代码根目录下winbuild目录下BUILD.WINDOWS.txt的提示
在源代码同级的目录下建立deps文件夹
此时的目录结构如下图（伪目录）

somedirectory\
|__curl-src
|    |_winbuild
|
|__deps
　　|_ lib
　　|_ include
　　|_ bin

我这里的deps文件夹目录是 E:\curl\deps
将编译openssl时候，安装目录E:\curl\openssl-1.0.2e\develop\include下的
openssl夹拷贝到E:\curl\deps\include\目录下；
将zlib源码根目录下的zconf.h、zlib.h和zutil.h拷贝到E:\curl\deps\include目录下。
将E:\curl\openssl-1.0.2e\develop\lib目录下的libeay32.lib和ssleay.lib拷贝到E:\curl\deps\lib目录下；
将zlib源码根目录下的zlib.lib拷贝到E:\curl\deps\lib目录下。
c.编译libcurl
命令行进入源代码根目录下 winbuild 目录

nmake RTLIBCFG=static /f Makefile.vc mode=static VC=14 WITH_DEVEL=E:\curl\deps WITH_SSL=static ENABLE_SSPI=no ENABLE_IPV6=no DEBUG=no

参数详细含义如下：

nmake /f Makefile.vc mode=<static or dll> <options>

where <options> is one or many of:
  VC=<6,7,8,9,10,11,12,14>     - VC versions
  WITH_DEVEL=<path>            - Paths for the development files (SSL, zlib, etc.)
                                 Defaults to sibbling directory deps: ../deps
                                 Libraries can be fetched at http://windows.php.net/downloads/php-sdk/deps/
                                 Uncompress them into the deps folder.
  WITH_SSL=<dll or static>     - Enable OpenSSL support, DLL or static
  WITH_CARES=<dll or static>   - Enable c-ares support, DLL or static
  WITH_ZLIB=<dll or static>    - Enable zlib support, DLL or static
  WITH_SSH2=<dll or static>    - Enable libSSH2 support, DLL or static
  ENABLE_SSPI=<yes or no>      - Enable SSPI support, defaults to yes
  ENABLE_IPV6=<yes or no>      - Enable IPv6, defaults to yes
  ENABLE_IDN=<yes or no>       - Enable use of Windows IDN APIs, defaults to yes
                                 Requires Windows Vista or later, or installation from:
                                 http://www.microsoft.com/downloads/details.aspx?FamilyID=AD6158D7-DDBA-416A-9109-07607425A815
  ENABLE_WINSSL=<yes or no>    - Enable native Windows SSL support, defaults to yes
  GEN_PDB=<yes or no>          - Generate Program Database (debug symbols for release build)
  DEBUG=<yes or no>            - Debug builds
  MACHINE=<x86 or x64>         - Target architecture (default is x86)
  
  Static linking of Microsoft's C RunTime (CRT):
==============================================
If you are using mode=static nmake will create and link to the static build of
libcurl but *not* the static CRT. If you must you can force nmake to link in
the static CRT by passing RTLIBCFG=static. Typically you shouldn't use that
option, and nmake will default to the DLL CRT. RTLIBCFG is rarely used and
therefore rarely tested. When passing RTLIBCFG for a configuration that was
already built but not with that option, or if the option was specified
differently, you must destroy the build directory containing the configuration
so that nmake can build it from scratch.

Legacy Windows and SSL
======================
When you build curl using the build files in this directory the default SSL
backend will be WinSSL (Windows SSPI, more specifically Schannel), the native
SSL library that comes with the Windows OS. WinSSL in Windows <= XP is not able
to connect to servers that no longer support the legacy handshakes and
algorithms used by those versions. If you will be using curl in one of those
earlier versions of Windows you should choose another SSL backend like OpenSSL.

3.验证

vs2015
添加好包含目录 ，附加库目录， 附加依赖项后，预处理器添加上BUILDING_LIBCURL

// staticLibcurlTest.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <iostream>
#include <curl.h>

using namespace std;

/**
* 一旦curl接收到数据，就会调用此回调函数
* buffer:数据缓冲区指针
* size:调试阶段总是发现为1
* nmemb:(memory block)代表此次接受的内存块的长度
* userp:用户自定义的一个参数
*/
size_t write_data(void* buffer, size_t size, size_t nmemb, void* userp)
{
	static int current_index = 0;

	cout << "current:" << current_index++;
	cout << (char*)buffer;
	cout << "---------------" << endl;

	int temp = *(int*)userp;    // 这里获取用户自定义参数
	return nmemb;
}

int main()
{
	curl_global_init(CURL_GLOBAL_ALL); // 首先全局初始化CURL
	CURL* curl = curl_easy_init(); // 初始化CURL句柄

	if (NULL == curl)
	{
		return 0;
	}

	int my_param = 1;    // 自定义一个用户参数

						 // 设置目标URL
	curl_easy_setopt(curl, CURLOPT_URL, "https://api.vxxx/gettime");
	// 设置接收到HTTP服务器的数据时调用的回调函数
	curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L);
	curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L);
	curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);
	// 设置自定义参数(回调函数的第四个参数)
	curl_easy_setopt(curl, CURLOPT_WRITEDATA, &my_param);
	// 执行一次URL请求
	CURLcode res = curl_easy_perform(curl);
	// 清理干净
	curl_easy_cleanup(curl);
	getchar();
	return 0;
}

参考：
https://blog.youkuaiyun.com/fm0517/article/details/91822880
https://blog.youkuaiyun.com/huangyimo/article/details/80337496