On 14 Dec 2023, at 4:13 AM, 2111191--- via petsc-users <[email protected]> wrote:

Dear SLEPc Developers,

I a am student from Tongji University. Recently I am trying to write a c++ program for matrix solving, which requires importing the PETSc library that you have developed. However a lot of errors occur in the cpp file when I use #include <petscts.h> directly. I also try to use extern "C" but it gives me the error in the picture below. Is there a good way to use the PETSc library in a c++ program? (I compiled using cmake and my compiler is g++ (GCC) 4.8.5 20150623 (Red Hat 4.8.5-44)).

This compiler (gcc 4.8.5) is known to not be C++11 compliant, but you are using the -std=c++11 flag. Furthermore, since version 3.18 (or maybe slightly later), PETSc requires a C++11-compliant compiler if using C++. Could you switch to a newer compiler, or try to reconfigure? Also, you should not put all the include inside an extern { }. In any case, you’ll need to send the compilation error log and configure.log to [email protected] <mailto:[email protected]> if you want further help, as we won’t be able to give a better diagnosis with just the currently provided information. Thanks, Pierre

My cmakelists.txt is:

cmake_minimum_required(VERSION 3.1.0)

set(CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE)

set(PETSC $ENV{PETSC_DIR}/$ENV{PETSC_ARCH}) set(SLEPC $ENV{SLEPC_DIR}/$ENV{PETSC_ARCH}) set(ENV{PKG_CONFIG_PATH} ${PETSC}/lib/pkgconfig:${SLEPC}/lib/pkgconfig)

set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11") set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99")

project(test)

add_executable(${PROJECT_NAME} eigen_test2.cpp) find_package(PkgConfig REQUIRED)

pkg_search_module(PETSc REQUIRED IMPORTED_TARGET PETSc) target_link_libraries(${PROJECT_NAME} PkgConfig::PETSc)

The testing code is:eigen_test2.cpp extern "C"{ //#include <petsc.h> #include <petscts.h> #include <petscdm.h> #include <petscdmda.h> #include <petscdraw.h> }

int main(int argc,char **argv) { return 0; }

Best regards

Weijie Xu