终端。例如，在我的OS X默认终端上，没有字符输出。

The output varies among different terminals. For example, on my OS X default terminal, no characters are output.

在您的情况下，输出☺大概是由于某些历史原因。简而言之，这是因为代码页437是将字符 0x01 映射到 U + 263A 的代码页， MS-DOS。

In your case, ☺ is output presumably due to some historical reasons. In short, this is because code page 437, which maps byte 0x01 to U+263A, is the character set of MS-DOS.