我已经按照一些说明构建了Visual Studio Code C/C++编译和调试环境。但是g++编译器只能编译选定的cpp文件，因此无法编译与cpp文件相关联的.h文件。然后终端显示“架构 x86_64 的未定义符号”错误。代码如下：

.ah 文件

    int func();

a.cpp 文件

    include <iostream>
    include "a.h"
    using namespace std;
    int func(){
        return 111;
    }

main.cpp 文件

    include "a.h"
    using namespace std;
    int main()
    {
        int b = func();
        cout << b << endl;
    }

Visual Studio 代码将使用如下命令

     g++ directory/main.cpp -o directory/main.out -g -Wall -fcolor-        diagnostics -std=c++11

此命令将引发“体系结构 x86_64 的未定义符号”错误我可以使用此新命令修复它

    g++ main.cpp a.cpp -o main.out.

所以问题是如何配置这些 json 文件来修复 g++ 编译问题。当我想使用某些库（例如 FFMpeg）时，如何正确链接 FFMpeg .h 文件。

我使用 rvm install ruby​​ 然后使用 gem install cocoapods ，bug run pod 命令总是引发错误：

 /Users/stanhu/.rvm/rubies/ruby-2.4.6/lib/ruby/site_ruby/2.4.0/rubygems/core_ext/kernel_require.rb:54:in `require': dlopen(/Users/stanhu/.rvm/gems/ruby-2.4.6/gems/ffi-1.12.2/lib/ffi_c.bundle, 9): Symbol not found: _ffi_type_double (LoadError)
  Referenced from: /Users/stanhu/.rvm/gems/ruby-2.4.6/gems/ffi-1.12.2/lib/ffi_c.bundle
  Expected in: flat namespace
 in /Users/stanhu/.rvm/gems/ruby-2.4.6/gems/ffi-1.12.2/lib/ffi_c.bundle - /Users/stanhu/.rvm/gems/ruby-2.4.6/gems/ffi-1.12.2/lib/ffi_c.bundle
    from /Users/stanhu/.rvm/rubies/ruby-2.4.6/lib/ruby/site_ruby/2.4.0/rubygems/core_ext/kernel_require.rb:54:in `require'
    from /Users/stanhu/.rvm/gems/ruby-2.4.6/gems/ffi-1.12.2/lib/ffi.rb:6:in `rescue in <top (required)>'
    from /Users/stanhu/.rvm/gems/ruby-2.4.6/gems/ffi-1.12.2/lib/ffi.rb:3:in `<top (required)>'
    from /Users/stanhu/.rvm/rubies/ruby-2.4.6/lib/ruby/site_ruby/2.4.0/rubygems/core_ext/kernel_require.rb:54:in `require'
    from /Users/stanhu/.rvm/rubies/ruby-2.4.6/lib/ruby/site_ruby/2.4.0/rubygems/core_ext/kernel_require.rb:54:in `require'
    from /Users/stanhu/.rvm/rubies/ruby-2.4.6/lib/ruby/gems/2.4.0/gems/ethon-0.12.0/lib/ethon.rb:2:in `<top (required)>'
    from /Users/stanhu/.rvm/rubies/ruby-2.4.6/lib/ruby/site_ruby/2.4.0/rubygems/core_ext/kernel_require.rb:54:in `require'
    from /Users/stanhu/.rvm/rubies/ruby-2.4.6/lib/ruby/site_ruby/2.4.0/rubygems/core_ext/kernel_require.rb:54:in `require'
    from /Users/stanhu/.rvm/rubies/ruby-2.4.6/lib/ruby/gems/2.4.0/gems/typhoeus-1.3.1/lib/typhoeus.rb:2:in `<top (required)>'
    from /Users/stanhu/.rvm/rubies/ruby-2.4.6/lib/ruby/site_ruby/2.4.0/rubygems/core_ext/kernel_require.rb:54:in `require'
    from /Users/stanhu/.rvm/rubies/ruby-2.4.6/lib/ruby/site_ruby/2.4.0/rubygems/core_ext/kernel_require.rb:54:in `require'
    from /Users/stanhu/.rvm/rubies/ruby-2.4.6/lib/ruby/gems/2.4.0/gems/cocoapods-1.9.0/lib/cocoapods/sources_manager.rb:5:in `<top (required)>'
    from /Users/stanhu/.rvm/rubies/ruby-2.4.6/lib/ruby/site_ruby/2.4.0/rubygems/core_ext/kernel_require.rb:54:in `require'
    from /Users/stanhu/.rvm/rubies/ruby-2.4.6/lib/ruby/site_ruby/2.4.0/rubygems/core_ext/kernel_require.rb:54:in …

就像下面的代码一样,当我使用一个块来回调时,我想让块返回void,但我找不到一个单词来做这个.

fun search(key:String, callback: ((novels:ResultInfo)->??)){