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显示）-The preparation of a read word process, from the input source, the identification of each word has an independent significance, namely, the basic reserved words, identifiers, constants, operators, delimiters five categories. And turn out all the internal code word and the word symbol itself value. (Encountered an error can be displayed " Error" , then skip the error part of the continued display)