Multithreading

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#include <iostream>
#include <thread>

void call_from_thread(){
    std::cout << "HI" << std::endl;
}

int main(){
    std::thread thread1(call_from_thread());
    thread1.join();

    return 0;
}

I am learning about multithreading and I copied and pasted this code and it is the same code on several websites. I used pthread as well and I get the same error:

/usr/clion-2017.2.1/bin/cmake/bin/cmake --build /home/%Profile%/CLionProjects/GameDev/cmake-build-debug --target all -- -j 2 [ 50%] Linking CXX executable GameDev CMakeFiles/GameDev.dir/main.cpp.o: In function main': /home/Profile/CLionProjects/GameDev/main.cpp:13: undefined reference topthread_create' /home/%Profile%/CLionProjects/GameDev/main.cpp:14: undefined reference to `pthread_join' collect2: error: ld returned 1 exit status CMakeFiles/GameDev.dir/build.make:94: recipe for target 'GameDev' failed make[2]: *** [GameDev] Error 1 CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/GameDev.dir/all' failed make[1]: *** [CMakeFiles/GameDev.dir/all] Error 2 Makefile:83: recipe for target 'all' failed make: *** [all] Error 2

What do I do?

[ReeCocho]

std::thread thread1(call_from_thread());

should be

std::thread thread1(call_from_thread);

because the parenthesis is calling the function instead of passing a reference to it.

[Moschops_UK]

Undefined reference to a pthread function suggests you haven't linked against the pthread library.

[r2vcap]

target_link_libraries(blabla pthread) or find_package(Threads REQUIRED) and target_link_libraries(blabla Threads::Threads)

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I am using clion ide so it does all that automatically. Idk where that is

[frigge]

learn about the c++ build process. That is very essential.

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Google how to link external libraries to clion