自上而下语法分析器设计,理解手工编写自上而下语法分析器的设计方法。1、　　在VC下打开gram.dsp，阅读工程gram，gram为一个加法（适当扩充可为四则）运算表达式的LL1递归下降语法分析器，规定其文法-Down parser design, design method of top-down parser understand writing manual. 1, open in VC gram.dsp, read engineering gram, gram as an additive (appropriate expansion to four) LL1 recursive arithmetic expressions down parser, the provisions of its grammar