用C语言采用模拟DFA算法编写一个扫描器（词法分析器）用来识别： 由任意个a或b开始后接aa再自加或自减1的字符串，即正规式r=(a|b)*aa(+|-)1描述的语言L（r）。 -Simulated DFA algorithm in C language to write a scanner (lexical analyzer) is used to identify: followed by any one of a or b aa longer self plus or decrem

一段简单的代码实现字符串的加减, 可以用于编程练习(A piece of code which implements the addition and subtraction of a string)