C++ problem with dlopen(), how to correct open it?

Question

I have try to open .so

#include <dlfcn.h>

int main() {
    void *handle;
    handle = dlopen("test.so",RTLD_LAZY );

    return 0;
}

compile by

g++ -ldl -o untitled5 main.cpp

and have such problem :

/usr/bin/ld: /tmp/ccQsDBYl.o: in function `main':
main.cpp:(.text+0x41): undefined reference to `dlopen'
/usr/bin/ld: main.cpp:(.text+0x56): undefined reference to `dlopen'
collect2: error: ld returned 1 exit status