Question

我正在使用facebook的proxygen库来构建一个简单的客户端示例。在一个目录中，我有两个目标文件，我如何链接它们：我正在使用：

g++ -std=c++11 -o my_echo CurlClientMain.o  CurlClient.o -lproxygenhttpserver -lfolly -lglog -lgflags -pthread

我认为我在上面的示例中缺少一些像-lgflags这样的链接器标志。也许包括一些-someflag将有助于编译。我怎么知道所有可能的库标志都可以像他们使用的那样-lproxyhttpserver。

简而言之，定义或定位所有这些库。我正在使用ubuntu。

这是我的错误消息

 In function `main':
/home/kshitij/proxygen/httpclient/samples/curl/CurlClientMain.cpp:91: undefined reference to `proxygen::HTTPConnector::HTTPConnector(proxygen::HTTPConnector::Callback*, folly::HHWheelTimer*)'
/home/kshitij/proxygen/httpclient/samples/curl/CurlClientMain.cpp:102: undefined reference to `proxygen::HTTPConnector::connect(folly::EventBase*, folly::SocketAddress const&, std::chrono::duration<long, std::ratio<1l, 1000l> >, std::map<folly::AsyncSocket::OptionKey, int, std::less<folly::AsyncSocket::OptionKey>, std::allocator<std::pair<folly::AsyncSocket::OptionKey const, int> > > const&, folly::SocketAddress const&)'
/home/kshitij/proxygen/httpclient/samples/curl/CurlClientMain.cpp:91: undefined reference to `proxygen::HTTPConnector::~HTTPConnector()'
/home/kshitij/proxygen/httpclient/samples/curl/CurlClientMain.cpp:99: undefined reference to `proxygen::HTTPConnector::connectSSL(folly::EventBase*, folly::SocketAddress const&, std::shared_ptr<folly::SSLContext> const&, ssl_session_st*, std::chrono::duration<long, std::ratio<1l, 1000l> >, std::map<folly::AsyncSocket::OptionKey, int, std::less<folly::AsyncSocket::OptionKey>, std::allocator<std::pair<folly::AsyncSocket::OptionKey const, int> > > const&, folly::SocketAddress const&, std::string const&)'
/home/kshitij/proxygen/httpclient/samples/curl/CurlClientMain.cpp:91: undefined reference to `proxygen::HTTPConnector::~HTTPConnector()'
CurlClient.o: In function `CurlService::CurlClient::connectSuccess(proxygen::HTTPUpstreamSession*)':
/home/kshitij/proxygen/httpclient/samples/curl/CurlClient.cpp:69: undefined reference to `proxygen::HTTPUpstreamSession::newTransaction(proxygen::HTTPTransactionHandler*)'
collect2: error: ld returned 1 exit status
kshitij@forgetit:~/proxygen/httpclient/samples/curl$ g++ -std=c++11 -o my_echo CurlClientMain.o  CurlClient.o -lproxygenhttpserver -lfolly -lglog -lgflags -pthread
CurlClientMain.o: In function `main':
/home/kshitij/proxygen/httpclient/samples/curl/CurlClientMain.cpp:91: undefined reference to `proxygen::HTTPConnector::HTTPConnector(proxygen::HTTPConnector::Callback*, folly::HHWheelTimer*)'
/home/kshitij/proxygen/httpclient/samples/curl/CurlClientMain.cpp:102: undefined reference to `proxygen::HTTPConnector::connect(folly::EventBase*, folly::SocketAddress const&, std::chrono::duration<long, std::ratio<1l, 1000l> >, std::map<folly::AsyncSocket::OptionKey, int, std::less<folly::AsyncSocket::OptionKey>, std::allocator<std::pair<folly::AsyncSocket::OptionKey const, int> > > const&, folly::SocketAddress const&)'
/home/kshitij/proxygen/httpclient/samples/curl/CurlClientMain.cpp:91: undefined reference to `proxygen::HTTPConnector::~HTTPConnector()'
/home/kshitij/proxygen/httpclient/samples/curl/CurlClientMain.cpp:99: undefined reference to `proxygen::HTTPConnector::connectSSL(folly::EventBase*, folly::SocketAddress const&, std::shared_ptr<folly::SSLContext> const&, ssl_session_st*, std::chrono::duration<long, std::ratio<1l, 1000l> >, std::map<folly::AsyncSocket::OptionKey, int, std::less<folly::AsyncSocket::OptionKey>, std::allocator<std::pair<folly::AsyncSocket::OptionKey const, int> > > const&, folly::SocketAddress const&, std::string const&)'
/home/kshitij/proxygen/httpclient/samples/curl/CurlClientMain.cpp:91: undefined reference to `proxygen::HTTPConnector::~HTTPConnector()'
CurlClient.o: In function `CurlService::CurlClient::connectSuccess(proxygen::HTTPUpstreamSession*)':
/home/kshitij/proxygen/httpclient/samples/curl/CurlClient.cpp:69: undefined reference to `proxygen::HTTPUpstreamSession::newTransaction(proxygen::HTTPTransactionHandler*)'
collect2: error: ld returned 1 exit status

Answer 1

我怎么知道所有可能的库标志都是可用的，就像他们使用的-lproxyhttpserver一样。

这取决于您的编译环境。

您似乎在linux中使用GNU编译器。有一个列出所有已安装的共享库的工具：

ldconfig -p

你会得到一个像这样的行列表

libpthread.so.0 (libc6,x86-64, OS ABI: Linux 2.6.32) => /lib/x86_64-linux-gnu/libpthread.so.0

删除lib前缀和扩展名.so.X，您将获得该库的名称。在这种情况下，它是pthread。要与libray链接，请使用选项-lNAME。所以，在此示例中为-lpthread。

简而言之，所有这些libs定义或定位

=>的右侧部分是图书馆的完整路径。

如何在c ++中完成链接？

1 个答案: