egcs 1.0.x (at least .2, .3a) doesn't know about the %a printf specifier. This is new to C9x and prints floating point numbers in hexadecimal. glibc 2.1 (and possibly 2.0) implements it; the test suite gets spurious warnings - warning: unknown conversion type character 0xa in format It'd be nice if egcs 1.1 knew about it. zw