CppCon 2015: Detlef Vollmann “Executors for C++ - A Long Story ..."从这个例子开始:
std::async([](){ std::cout << "Hello "; });
std::async([](){ std::cout << "World!\n"; });
C++ reference显示std::async
在<future>
和 std::cout
在<iostream>
.构建工作缺少什么?
$ cat >hw.cpp <<EOF
> #include <iostream>
> int main(){
> std::cout << "Hello World!\n";
> }
> EOF
$ clang++ -std=c++14 hw.cpp
$ ./a.out
Hello World!
$ cat >cppcon15.cpp <<EOF
> #include <future>
> #include <iostream>
> int main(){
> std::async([](){ std::cout << "Hello "; });
> std::async([](){ std::cout << "World!\n"; });
> }
> EOF
$ clang++ -std=c++14 cppcon15.cpp
/tmp/cppcon15-4f0a58.o: In function `std::thread::thread<std::__future_base::_Async_state_impl<std::_Bind_simple<main::$_1 ()>, void>::_Async_state_impl(std::_Bind_simple<main::$_1 ()>&&)::{lambda()#1}>(std::__future_base::_Async_state_impl<std::_Bind_simple<main::$_1 ()>, void>::_Async_state_impl(std::_Bind_simple<main::$_1 ()>&&)::{lambda()#1}&&)':
cppcon15.cpp:(.text+0x2cf6): undefined reference to `pthread_create'
/tmp/cppcon15-4f0a58.o: In function `std::thread::thread<std::__future_base::_Async_state_impl<std::_Bind_simple<main::$_0 ()>, void>::_Async_state_impl(std::_Bind_simple<main::$_0 ()>&&)::{lambda()#1}>(std::__future_base::_Async_state_impl<std::_Bind_simple<main::$_0 ()>, void>::_Async_state_impl(std::_Bind_simple<main::$_0 ()>&&)::{lambda()#1}&&)':
cppcon15.cpp:(.text+0x6bb6): undefined reference to `pthread_create'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
最佳答案
您需要使用 -pthread
进行编译,以便链接器允许您使用异步/ future /线程功能。
关于c++ - std::async([](){ std::cout<< "Hello "; }) 构建错误,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/34821747/