问题描述
我在我的 mac 机器上写了一些代码，它运行得很好，但是当我把它移植到 Linux 机器上时，我得到一个 对 curl_easy_init 的未定义引用
I have some code I wrote on my mac machine and it has been working perfectly but when I port it over to a Linux machine I get an undefined reference to curl_easy_init
我的编译器标志包括用于链接的 -lcurl.
My compiler flags include a -lcurl for linking.
这是我的链接方式:
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -L/curl/lib/dir -lcurl")
我试过有和没有 -L/curl/lib/dir
Curl 安装在这台机器上:
Curl is installed on this machine:
$ curl --version
curl 7.47.0 (x86_64-pc-linux-gnu) libcurl/7.47.0 GnuTLS/3.4.10 zlib/1.2.8 libidn/1.32 librtmp/2.3
Protocols: dict file ftp ftps gopher http https imap imaps ldap ldaps pop3 pop3s rtmp rtsp smb smbs smtp smtps telnet tftp
Features: AsynchDNS IDN IPv6 Largefile GSS-API Kerberos SPNEGO NTLM NTLM_WB SSL libz TLS-SRP UnixSockets
推荐答案
Never 将 -l 标志添加到 CMAKE_EXE_LINKER_FLAGS 和 >CMAKE_CXX_FLAGS(标志 -l 用于链接器，而不是编译器).
Never add -l flags to CMAKE_EXE_LINKER_FLAGS and moreover to CMAKE_CXX_FLAGS (the flag -l is for the linker, not for a compiler).
对于与库的链接，请使用 target_link_libraries:它是专门用于该目的:
For link with libraries use target_link_libraries: it is specifically intended for that purpose:
target_link_libraries(<your-executable> curl)
当您向 *_FLAGS 变量添加标志时，该标志将在链接器的命令行中源文件之前(实际上是目标文件)添加.如果源文件使用库中的某些函数，则链接器找不到它.
When you add a flag to *_FLAGS variable, the flag is added before the source file (object file actually) in the linker's command-line. If the source file uses some function from the library, then the linker cannot find it.
相反，由命令target_link_libraries 生成的标志被添加到链接器命令行中的源文件之后.
As opposite, a flag produced by command target_link_libraries is added after the source file in the linker's command line.
这篇关于CMAKE_CXX_FLAGS 中的标志“-l"不起作用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！