用C语言实现词法分析器.doc

用C语言实现词法分析器#include#include#include#define _KEY_WORD_END waiting for your expandingtypedef struct int typenum; char *word; WORD; char input255; char token255=; int p_input; int p_token; char ch; char* rwtab=main,if,then,while,do,static,int,double,struct,break,else,long,switch,case,typedef,char,return,const,float,short,continue,for,void,defult,sizeof,do,printf,include,scanf,_KEY_WORD_END; WORD* scaner(); int main() int over=1; WORD* oneword= malloc(sizeof(WORD); printf(Enter Your words(end with $):); scanf(%$s,input); p_input=0; printf(Your words:n%sn,input); while(overtypenumtypenum,oneword-word); over=oneword-typenum; / printf(npress $ to exit: ); scanf(%$s,input); system(pause); return 0; /* char m_getch() ch=inputp_input; p_input=p_input+1; return(ch); /得到字符 void getbc() while(ch= | ch=10) ch=inputp_input; p_input=p_input+1; /去空格 void concat() tokenp_token=ch; p_token=p_token+1; tokenp_token=0; /连接单词 int letter() if(ch=a&ch=A&ch=0&ch typenum = 10;myword - word = ;p_token = 0;m_getch();getbc();if(letter()while(letter()|digit()concat();m_getch();retract(); myword - typenum =reserve(); myword - word = token; printf(n);return(myword);else if(digit()while(digit()concat();m_getch();retract(); myword - typenum = 20; myword - word = token; printf(n);return(myword);else switch(ch)case=:m_getch(); if(ch = =)myword - typenum = 39;myword - word = =;printf(n);return(myword); retract(); myword - typenum = 21; myword - word = =; printf(n); return(myword);break;case+: myword - typenum = 22; myword - word = +; printf(n); return(myword);break;case-: myword - typenum = 23; myword - word = -; printf(n); return(myword);break;case*: myword - typenum = 24; myword - word = *; printf(n); return(myword);break;case/: myword - typenum = 25; myword - word = /; printf(n); return(myword);break;case(: myword - typenum = 26; myword - word = (; printf(n); return(myword);break;case): myword - typenum = 27; myword - word = ); printf(n); return(myword);break;case: myword - typenum = 28; myword - word = ; printf(n); return(myword);break;case: myword - typenum = 29; myword - word = ; printf(n); return(myword);break;case: myword - typenum = 30; myword - word = ; printf(n); return(myword);break;case: myword - typenum = 31; myword - word = ; printf(n); return(myword);break;case,: myword - typenum = 32; myword - word = ,; printf(n); return(myword);break;case: myword - typenum = 33; myword - word = :; printf(n); return(myword);break;case;: myword - typenum = 34; myword - word = ; printf(n); return(myword);break;case:m_getch();if(ch = =)myword - typenum = 37;myword - word = =;printf(n);return(myword);retract(); myword - typenum = 35; myword - word = ; printf(n); return(myword);break;case typenum = 38;myword - word = typenum = 36; myword - word = typenum = 40;myword - word = !=;printf(n);return(myword);retract(); myword - typenum = -1; myword - word = ERROR; printf(n); return(myword);break;case0: myword - typenum = 1000; myword - word = OVER; printf(n); return(myword);break;case #: myword - typenum = 41; myword - word = #; printf(n); return(myword);break;case : myword - typenum = 41; myword - word = ; printf(n); return(myword);break