int test_endianness() { union doubleword { double d; unsigned long u[2]; } dw; dw.d = 10; return dw.u[0] != 0 ? 1 : 0; } int test_endianness_vol() { union doubleword { volatile double d; volatile long u[2]; } dw; dw.d = 10; return dw.u[0] != 0 ? 1 : 0; } main () { if (test_endianness () != test_endianness_vol ()) abort (); exit (0); }