# test formatting floats with large precision, that it doesn't overflow the buffer def test(num, num_str): if num == float("inf") or num == 0.0 and num_str != "0.0": # skip numbers that overflow or underflow the FP precision return for kind in ("e", "f", "g"): # check precision either side of the size of the buffer (32 bytes) for prec in range(23, 36, 2): fmt = "%." + "%d" % prec + kind s = fmt % num check = abs(float(s) - num) if num > 1: check /= num if check > 1e-6: print("FAIL", num_str, fmt, s, len(s), check) # check most powers of 10, making sure to include exponents with 3 digits for e in range(-101, 102): num = pow(10, e) test(num, "1e%d" % e)