編譯原理_詞法分析器_實(shí)驗(yàn)報(bào)告

1、 詞法分析器實(shí)驗(yàn)報(bào)告實(shí)驗(yàn)?zāi)康模涸O(shè)計(jì)、編制、調(diào)試一個(gè)詞法分析子程序識別單詞，加深對詞法分析原理的理解。功能描述：該程序要實(shí)現(xiàn)的是一個(gè)讀單詞過程，從輸入的源程序中，識別出各個(gè)具有獨(dú)立意義的單詞，即基本保留字、標(biāo)識符、常數(shù)、運(yùn)算符、分隔符五大類。并依次輸出各個(gè)單詞的部編碼及單詞符號自身值。（遇到錯(cuò)誤時(shí)可顯示“Error！”，然后跳過錯(cuò)誤部分繼續(xù)進(jìn)行）設(shè)計(jì)思想：設(shè)計(jì)該詞法分析器的過程中雖然沒有實(shí)際將所有的狀態(tài)轉(zhuǎn)移表建立出來，但是所用的思想是根據(jù)狀態(tài)轉(zhuǎn)移表實(shí)現(xiàn)對單詞的識別。首先構(gòu)造一個(gè)保留字表,然后,每輸入一個(gè)字符就檢測應(yīng)該進(jìn)入什么狀態(tài),并將該字符連接到d串后繼續(xù)輸入,如此循環(huán),最后根據(jù)所在的接受狀態(tài)以

2、及保留字表識別單詞。符號表：記號類別屬性值ws-const保留字1var保留字1call保留字1begin保留字1if保留字1while保留字1do保留字1odd保留字1end保留字1then保留字1procedure保留字1=運(yùn)算符2<運(yùn)算符2<=運(yùn)算符2<>運(yùn)算符2>運(yùn)算符2>=運(yùn)算符2*運(yùn)算符2+運(yùn)算符2-運(yùn)算符2/運(yùn)算符2:=運(yùn)算符2ident標(biāo)識符3number常數(shù)4(分隔符5)分隔符5;分隔符5,分隔符5.分隔符5狀態(tài)轉(zhuǎn)換圖：標(biāo)識符及保留字：Startletterletter or digittnumber:70214365startotherd

3、igit.digitE+ | -digitdigitdigitdigitEdigit*otherother關(guān)系操作符：start<other= (<=, 2)>=other>=* (<>, 2) (<,2) (=, 2) (>=, 2)(>, 2)：=（：=，2）分隔符：start;(),.( ; ,5)( (,5)( ),5)( , ,5)( . ,5)算術(shù)運(yùn)算符：start+-*/( + ,2)( -,2)( *,2)( / ,2)使用環(huán)境：Windows xp下的visual c+6.0程序測試：input1 :int a,b;a=b

4、+2;input2:while(a>=0)do7x=x+6.7E+23;end;input3:begin:x:=9if x>0 then x:=x+1;while a:=0 dob:=2*x/3,c:=a;end;9 / 9output1:3,int3,a5,3,b5,;3,a2,=3,b2,+4,25,;output2:1,while5,(3,a2,>=4,05,)1,doerror line 32,=3,x2,+4,6.7E+235,;1,end5,;output3:1,beginerror line 13,x2,:=4,91,if3,x2,>4,01,then3,

5、x2,:=3,x2,+4,15,;1,while3,a2,:=4,01,do3,b2,:=4,22,*3,x2,/4,35,3,c2,:=3,a5,;1,end5,;測試結(jié)果與預(yù)期結(jié)果一致源程序代碼：#include<stdio.h>#include<string.h>void main()int i=0,j,k=0,state=1,f=0,linenum=1;char a1110="const","var","call","begin","if","while

6、","do","odd","end","then","procedure"char b,d40="0" freopen("input.txt","r",stdin); freopen("output.txt","w",stdout); b=getchar(); while(b!=EOF)/*判斷所輸入字符是否為結(jié)束符*/if(b=' '|b='n'|b=&

7、#39;t')/*濾過空格、換行等分隔符號*/ if(b='n') linenum+;b=getchar();else if(b>='a'&&b<='z')|(b>='A'&&b<='Z')/*識別標(biāo)識符以及保留字*/di+=b; b=getchar();while(b>='a'&&b<='z')|(b>='A'&&b<='Z')|(

8、b>='0'&&b<='9') di+=b;b=getchar();for(j=0;j<11;j+)/*查詢保留字表確定該單詞是否是保留字*/ if(strcmp(d,aj)=0) printf("1,%sn",d); k=1; break;if(k=0)/*在保留字表中沒有查到該單詞，是標(biāo)識符*/ printf("3,%sn",d);for(j=0;j<=i;j+)dj='0' i=0;k=0;else if(b>='0'&&b

9、<='9')/*識別常數(shù)*/ di+=b; b=getchar(); while(f!=1) switch (state) case 1: if(b>='0'&&b<='9') state=1; di+=b; b=getchar(); else if(b='.') state=2;di+=b;b=getchar(); else if(b='E') state=4;di+=b;b=getchar(); else state=7; break; case 2: if(b>=

10、9;0'&&b<='9') state=3; di+=b; b=getchar(); else state=8; break; case 3: if(b>='0'&&b<='9') state=3; di+=b; b=getchar(); else if(b='E') state=4;di+=b;b=getchar(); else state=7; break; case 4: if(b='+'|b='-') state=5;di+=b;b=

11、getchar(); else if(b>='0'&&b<='9') state=6;di+=b;b=getchar(); else state=8; break; case 5: if(b>='0'&&b<='9') state=6;di+=b;b=getchar(); else state=8; break; case 6: if(b>='0'&&b<='9') state=6;di+=b;b=getchar()

12、; else state=7; break; case 7: f=1;break; case 8: f=1;break; if(state=7&&(b<'a'|b>'z')&&(b<'A'|b>'Z') printf("4,%sn",d); else if(state=7&&(b>='a'&&b<='z')|(b>='A'&&b<=

13、9;Z')/*數(shù)字后接字母的出錯(cuò)控制*/ while(b>='a'&&b<='z')|(b>='A'&&b<='Z') di+=b; b=getchar(); printf("error line %dn",linenum); else printf("error line %dn",linenum); for(j=0;j<=i;j+)dj='0' i=0; f=0; state=1;else if(b=&

14、#39;<')/*識別'<'、'<='和'<>'*/ di+=b; b=getchar(); if(b='='|b='>') di+=b; b=getchar(); printf("2,%sn",d); for(j=0;j<=i;j+)dj='0' i=0; else printf("2,%sn",d); for(j=0;j<=i;j+)dj='0'i=0; else if(b='

15、>')/*識別'>'和'>='*/ di+=b; b=getchar(); if(b='=') di+=b; b=getchar(); printf("2,%sn",d); for(j=0;j<=i;j+)dj='0' i=0; else printf("2,%sn",d); for(j=0;j<=i;j+)dj='0'i=0; else if(b=':')/*識別':='*/ di+=b; b=getch

16、ar(); if(b='=') di+=b; b=getchar(); printf("2,%sn",d); else printf("error line %dn",linenum); for(j=0;j<=i;j+)dj='0' i=0; else if(b='*'|b='+'|b='-'|b='/'|b='=')/*識別運(yùn)算符*/ printf("2,%cn",b); b=getchar(); else if(b='('|b=')'|b=','|b