pl0词法分析器(C语言版)(共6页)

1、精选优质文档-倾情为你奉上#include<stdio.h>#include<string.h>#include<stdlib.h>void init();void getsym();enum symbolnul,ident,number,plus,minus,times,slash,oddsym,eql,neq,lss,leq,gtr,geq,lparen,rparen,comma,semicolon,period,becomes,beginsym,endsym,ifsym,thensym,whilesym,writesym,readsym,dosym,c

2、allsym,constsym,varsym,procsym,programsym,;#define norw 14#define al 10#define nmax 10char word norwal;char ch;enum symbol sym;enum symbol wsymnorw;enum symbol ssym256;FILE *fin,*fout;void main()printf("please input outfile's name:n"); /词法分析之后的结果要输出到的文件char outname30,inname30;scanf(&qu

3、ot;%s",outname);if(fout=fopen(outname,"w")=NULL)printf("cannot open output file!");exit(0);printf("please input infile's name:n"); /需要词法分析的源程序scanf("%s",inname);if(fin=fopen(inname,"r")=NULL)printf("cannot open file!n");exit(0);ch=

4、fgetc(fin);while(ch!=EOF)getsym();/读取源文件void getsym()long m; char idal+1,aal+1;int i,k;init();if(ch=' '|ch=10|ch=9)ch=fgetc(fin);elseif(ch>='a'&&ch<='z'|ch>='A'&&ch<='Z')k=0; doif(k<al)ak=ch; k+;ch=fgetc(fin);while (ch>='a

5、'&&ch<='z'|ch>='0'&&ch<='9')|(ch>='A'&&ch<='Z'|ch>='0'&&ch<='9');ak=0; strcpy(id,a); for(i=0;i<norw;i+)if(strcmp(id,wordi)=0)sym=wsymi; printf("%s %ssymn",id,id); fprintf(fou

6、t,"%s %ssymn",id,id);break;elseif(i=(norw-1)sym=ident; printf("%s identn",id); fprintf(fout,"%s identn",id);elseif(ch>='0'&&ch<='9')k=0; m=0; sym=number; dom=10*m+ch-'0' k+; ch=getc(fin);while(ch>='0'&&ch<='

7、;9');if(k>=nmax)printf(" error!数值太大！ n");/exit(0);printf("%d numbern",m);fprintf(fout,"%d numbern",m); elseif(ch=':') ch=getc(fin);if(ch='=')sym=becomes; printf(":= becomesn");fprintf(fout,":= becomesn"); ch=fgetc(fin);elsesym=

8、nul; printf(": nuln");fprintf(fout,": nuln");elseif(ch='<')ch=fgetc(fin); if(ch='=')sym=leq; printf("<= lepn");fprintf(fout,"<= lepn"); ch=fgetc(fin); elsesym=lss; printf("< lssn");fprintf(fout,"< lssn"); else

9、if(ch='>')ch=fgetc(fin);if(ch='=')sym=geq; printf(">= geqn");fprintf(fout,">= geqn"); ch=fgetc(fin);elsesym=gtr; printf("> gtrn"); fprintf(fout,"> gtrn");elsesym=ssymch;if(ch='+')printf("+ plusn");fprintf(fout,&

10、quot;+ plusn");ch=fgetc(fin);elseif(ch='-')printf("- minusn");fprintf(fout,"- minusn");ch=fgetc(fin);elseif(ch='*')printf("* timesn");fprintf(fout,"* timesn");ch=fgetc(fin);elseif(ch='/')printf("/ slashn");fprintf(fout,&q

11、uot;/ slashn");ch=fgetc(fin);elseif(ch='(')printf("( lparenn");fprintf(fout,"( lparenn");ch=fgetc(fin);elseif(ch=')')printf(") rparenn");fprintf(fout,") rparenn");ch=fgetc(fin);elseif(ch='=')printf("= eqln");fprintf(fout,

12、"= eqln");ch=fgetc(fin);elseif(ch=',')printf(", comman");fprintf(fout,", comman");ch=fgetc(fin);elseif(ch='#')printf("# neqn");fprintf(fout,"# neqn");ch=fgetc(fin);elseif(ch='.')printf(". periodn");fprintf(fout,"

13、;. periodn");ch=fgetc(fin);elseif(ch='')printf(" semicolnn");fprintf(fout," semicolnn");ch=fgetc(fin);elseprintf("%c nuln",ch);fprintf(fout,"%c nuln",ch);ch=fgetc(fin);/对关键字等实现初始化void init()int i;for(i=0;i<=255;i+)ssymi=nul;ssym'+'=plus

14、;ssym'-'=minus;ssym'*'=times;ssym'/'=slash;ssym'('=lparen;ssym')'=rparen;ssym'='=eql;ssym','=comma;ssym'.'=period;ssym'#'=neq;ssym''=semicolon;strcpy(&(word00),"begin");strcpy(&(word10),"call"

15、);strcpy(&(word20),"const");strcpy(&(word30),"do");strcpy(&(word40),"end");strcpy(&(word50),"if");strcpy(&(word60),"odd");strcpy(&(word70),"procedure");strcpy(&(word80),"read");strcpy(&(word90),"program");strcpy(&(word100),"var");strcpy(&(word110),"whlie");strcpy(&(word120),"write");strc