是将输入的源程序进行划分，给出基本符号（token）的序列，并掠过注解和空格等分隔符号。基本符号是与输入的语言定义的词法所规定的终结符。

本实验要求学生编制一个读单词过程，从输入的源程序中，识别出各个具有独立意义的单词，即基本保留字、标识符、常数、运算符、分隔符五大类。并依次输出各个单词的内部编码及单词符号自身值。（遇到错误时可显示“Error”，然后跳过错误部分继续进行

-Is the input source program division, and gives the basic symbol (token) sequence, and skim over comments and Spaces and separator. Basic symbol is with the input language definition of the morphology by the end of the operator.

The experiment students are required to prepare a read words process, from the input source program, identify each independent meaning of words, namely basic reserved words, identifier, constant, operators, separator five categories. And in turn output each word internal coding and word sign their own value. (meet mistake can show "Error", and then skip the wrong part to continue