undefined reference to `omp_get_wtime'

1
votes

i learn c++, OpenMP. I have tried compile my program with omp_get_wtime and it doesn't work, but when i deleted this, it works. i must add something, but what and where. In openmptryflags or Cmakelists? 

snap/clion/61/bin/cmake/linux/bin/cmake --build /home/bapah/CLionProjects/omp1/cmake-build-debug --target omp1 -- -j 6
[ 50%] Linking CXX executable omp1
CMakeFiles/omp1.dir/main.cpp.o: In function `main':
/home/bapah/CLionProjects/omp1/main.cpp:36: undefined reference to `omp_get_wtime'
collect2: error: ld returned 1 exit status
CMakeFiles/omp1.dir/build.make:83: recipe for target 'omp1' failed
make[3]: *** [omp1] Error 1
CMakeFiles/Makefile2:72: recipe for target 'CMakeFiles/omp1.dir/all' failed
make[2]: *** [CMakeFiles/omp1.dir/all] Error 2
CMakeFiles/Makefile2:84: recipe for target 'CMakeFiles/omp1.dir/rule' failed
make[1]: *** [CMakeFiles/omp1.dir/rule] Error 2
Makefile:118: recipe for target 'omp1' failed
make: *** [omp1] Error 2
1
c++cmakeclion
Sounds like you may be missing -fopenmp. Can you add the compiler or linker command lines to the question? – user4581301
where i must add -fopenmp? – Dima Rodionov
I'm afraid I don't know. I use different build tools. – user4581301
what do you use? What better for ubuntu.I use Clion and Cmake – Dima Rodionov
how do you add -fopenmp in your tools? – Dima Rodionov

1 Answers

3
votes

Solution : add to CMakeList.txt 

SET_TARGET_PROPERTIES(omp1 PROPERTIES COMPILE_FLAGS "-fopenmp"
    LINK_FLAGS "-fopenmp")

P.s. omp1 - name your project.

P.p.s. also you can write target_link_libraries(omp1 -fopenmp)