[Sun C++ 5.9] 0.char test failed due to different binary representation of "long double ld1 = 0" and "long double ld2 = 0."

$ cat test.cpp && CC test.cpp -o test && ./test
#include <cassert>
#include <cstring>

int main ()
{
    long double ld1 = 0;
    long double ld2 = 0.;
    
    assert (ld1 == ld2);
    assert (0 == memcmp (&ld1, &ld2, sizeof (ld1)));
    
    return 0;
}
test: test.cpp:10: Assertion `0 == memcmp (&ld1, &ld2, sizeof (ld1))' failed.
Aborted