(6.1.3.4) The value of an integer character constant that contains a character or escape sequence not represented in the basic execution character set or the extended character set for a wide character constant（包含一个字符的整型字符常量的值或不以基本执行字符集或宽字符常量的扩展字符集表示的换码序列的值）：

它是最右边字符的数值。例如，'\q' 等于 'q'。如果这样的换码序列出现，则会发出警告。