问题描述

错误信息如下

/usr/bin/ld: CMakeFiles/flow_server.dir/reactor/Reactor_demo.cpp.o: in function `main':
/tmp/cpp_flow_server/reactor/Reactor_demo.cpp:106: multiple definition of `main'; CMakeFiles/flow_server.dir/main.cpp.o:/tmp/cpp_flow_server/main.cpp:38: first defined here
collect2: error: ld returned 1 exit status
gmake[3]: *** [CMakeFiles/flow_server.dir/build.make:145: flow_server] Error 1
gmake[2]: *** [CMakeFiles/Makefile2:83: CMakeFiles/flow_server.dir/all] Error 2
gmake[1]: *** [CMakeFiles/Makefile2:90: CMakeFiles/flow_server.dir/rule] Error 2
gmake: *** [Makefile:124: flow_server] Error 2

我们主要看这一行即可

/tmp/cpp_flow_server/reactor/Reactor_demo.cpp:106: multiple definition of `main'; CMakeFiles/flow_server.dir/main.cpp.o:/tmp/cpp_flow_server/main.cpp:38: first defined here

意思是 /tmp/cpp_flow_server/reactor/Reactor_demo.cpp 文件的106行里面有个main函数，而/tmp/cpp_flow_server/main.cpp 的38行也有个main函数，一个项目中不能同时有2个main函数，属于是重复定义了；

经过查看，确实是有2个main函数，
第一个main函数：

第二个main函数：

解决方案

想要解决这个问题很简单，只需要注释掉其中一个main函数即可，删掉也行

然后点击main.cpp里面的绿色三角形；

构建过程中也没有报错

顺利运行起来了