CODEWITHSUNDEEP
c++c++11pthreadsclion
A. Lopez
A. Lopez

Reputation: 91

Undefined reference to pthread CLion

I'm trying to run this simple thread c++ program in CLion

#include <iostream>
#include <thread>

using namespace std;


//Start of the thread t1
 void hello() {
     cout << "Hello,concurrent world!" << endl; }



 int main() {
     thread t1(hello);     // spawn new thread that calls hello()

     cout << "Concurrency has started!" << endl;
     t1.join();            

     cout << "Concurrency completed!";

     return 0;
   }

My problem is that there's an error of undefined reference to pthread, and I don't undestand what I'm doing wrong... please notice that I'm doing this on CLion.

Upvotes: 9

Views: 20039

Answers (5)

ingconti
ingconti

Reputation: 11666

As per CLion 2021.3.3, no need to specify any additional settings:

Simply be sure to start from C and not C++ and select C 99.

--

cmake_minimum_required(VERSION 3.21)
project(threads01 C)

set(CMAKE_C_STANDARD 99)

add_executable(threads01 main.c)

Upvotes: 0

BullyWiiPlaza
BullyWiiPlaza

Reputation: 19233

In CMake first find the package:

find_package(Threads REQUIRED)

Then link against it:

target_link_libraries(${PROJECT_NAME} Threads::Threads)

Now the build will succeed the linking step.

Upvotes: 5

Le Danh
Le Danh

Reputation: 403

In CLion, to compile with flag -pthread you should add the following line to CMakeLists.txt (I've tested and it works):

SET(CMAKE_CXX_FLAGS -pthread)

Upvotes: 25

Jon Deaton
Jon Deaton

Reputation: 4409

You have to compile with flag -lpthread or -pthread (its usually advised to usepthread). If you're using CLion then you will need to edit CMakeLists.txt to ensure that your code is compiled with this flag by setting compiler flags with a command like:

SET( CMAKE_CXX_FLAGS  "<other compiler flags> -pthread")

You can learn more about these options on this post.

Upvotes: 0

Nate M
Nate M

Reputation: 104

Make sure you are linking to pthread in the end of your CMakeLists.txt

target_link_libraries(${PROJECT_NAME} pthread)

Upvotes: 0

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