语义分析器，将语义分析程序编制成子程序，在语法分析器分析出各语法单位后，分析其含义，并将可执行语句或表达式翻译为四元式输出，并将错误信息输出。-Semantic analyzer, semantic analysis program compiled subroutines, in the parser analyzes the syntax of the unit, analyze its meaning, and translated into an executable statement