所有的ASCII码都可以用“\”加数字（一般是8进制数字）来表示。而C中定义了一些字母前加 \ 来表示常见的那些不能显示的ASCII字符，如\0,\t,\n等，就称为转义字符，因为后面的字符，都不是它本来的ASCII字符意思了。-All ASCII code can be represented by " \"　plus the number (typically 8 hexadecimal numbers). And C is defined in a number of letters before adding " \"　to indicate that the common ASCII characters can not be displayed, such as \ 0, \ t, \ n, etc., is called the escape character, because behind the character, is not it already ASCII characters mean.