1、词法分析
/*cifa fenxi chengxu*/
#include <stdio.h>
#include <ctype.h>
#include <alloc.h>
#include <stdlib.h>
#include <string.h>
#define NULL 0
FILE *fp;
char cbuffer;
char *key[8]={"if","else","for","while","do","return","break","continue"};
char *border[6]={",",";","{","}","(",")"};
char *arithmetic[4]={"+","-","*","/"};
char *relation[6]={"<","<=","=",">",">=","<>"};
char *consts[20];
char *label[20];
int constnum=0,labelnum=0;
int search(char searchchar[],int wordtype)
{
int i=0;
switch (wordtype) {
case 1:for (i=0;i<=7;i++)
{
if (strcmp(key[i],searchchar)==0)
return(i+1);
}
case 2:{for (i=0;i<=5;i++)
{
if (strcmp(border[i],searchchar)==0)
return(i+1);
} return(0);
}
case 3:{for (i=0;i<=3;i++)
{
if (strcmp(arithmetic[i],searchchar)==0)
{
return(i+1);
}
}
return(0);
}
case 4:{for (i=0;i<=5;i++)
{
if (strcmp(relation[i],searchchar)==0)
{
return(i+1);
}
}
return(0);
}
case 5:{for (i=0;i<=constnum;i++)
{
if (strcmp(consts[i],searchchar)==0)
{
return(i+1);
}
}
consts[i-1]=(char *)malloc(sizeof(searchchar));
strcpy(consts[i-1],searchchar);
constnum++;
return(i);
}
case 6:{for (i=0;i<=labelnum;i++)
{
if (strcmp(label[i],searchchar)==0)
{
return(i+1);
}
}
label[i-1]=(char *)malloc(sizeof(searchchar));
strcpy(label[i-1],searchchar);
labelnum++;
return(i);
}
}
}
char alphaprocess(char buffer)
{
int atype;
int i=-1;
char alphatp[20];
while ((isalpha(buffer))||(isdigit(buffer)))
{
alphatp[++i]=buffer;
buffer=fgetc(fp);
}
alphatp[i+1]='"0';
if (atype=search(alphatp,1))
printf("%s (1,%d)"n",alphatp,atype-1);
else
{
atype=search(alphatp,6);
printf("%s (6,%d)"n",alphatp,atype-1);
}
return(buffer);
}
char digitprocess(char buffer)
{
int i=-1;
char digittp[20];
int dtype;
while ((isdigit(buffer)))
{
digittp[++i]=buffer;
buffer=fgetc(fp);
}
digittp[i+1]='"0';
dtype=search(digittp,5);
printf("%s (5,%d)"n",digittp,dtype-1);
return(buffer);
}
char otherprocess(char buffer)
{
int i=-1;
char othertp[20];
int otype,otypetp;
othertp[0]=buffer;
othertp[1]='"0';
if (otype=search(othertp,3))
{
printf("%s (3,%d)"n",othertp,otype-1);
buffer=fgetc(fp);
goto out;
}
if (otype=search(othertp,4))
{
buffer=fgetc(fp);
othertp[1]=buffer;
othertp[2]='"0';
if (otypetp=search(othertp,4))
{
printf("%s (4,%d)"n",othertp,otypetp-1);
goto out;
}
else
othertp[1]='"0';
printf("%s (4,%d)"n",othertp,otype-1);
goto out;
}
if (buffer==':')
{
buffer=fgetc(fp);
if (buffer=='=')
printf(":= (2,2)"n");
buffer=fgetc(fp);
goto out;
}
else
{
if (otype=search(othertp,2))
{
printf("%s (2,%d)"n",othertp,otype-1);
buffer=fgetc(fp);
goto out;
}
}
if ((buffer!='"n')&&(buffer!=' '))
printf("%c error,not a word"n",buffer);
buffer=fgetc(fp);
out: return(buffer);
}
void main()
{
int i;
for (i=0;i<=20;i++)
{
label[i]=NULL;
consts[i]=NULL;
};
if ((fp=fopen("example.c","r"))==NULL)
printf("error");
else
{
cbuffer = fgetc(fp);
while (cbuffer!=EOF)
{
if (isalpha(cbuffer))
cbuffer=alphaprocess(cbuffer);
else if (isdigit(cbuffer))
cbuffer=digitprocess(cbuffer);
else cbuffer=otherprocess(cbuffer);
}
printf("over"n");
getchar();
}
}
2、LL（1）
/*LL(1)分析法源程序，只能在VC++中运行 */
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<dos.h>
char A[20];/*分析栈*/
char B[20];/*剩余串*/
char v1[20]={'i','+','*','(',')','#'};/*终结符 */
char v2[20]={'E','G','T','S','F'};/*非终结符 */
int j=0,b=0,top=0,l;/*L为输入串长度 */
typedef struct type/*产生式类型定义 */
{
char origin;/*大写字符 */
char array[5];/*产生式右边字符 */
int length;/*字符个数 */
}type;
type e,t,g,g1,s,s1,f,f1;/*结构体变量 */
type C[10][10];/*预测分析表 */
void print()/*输出分析栈 */
{
int a;/*指针*/
for(a=0;a<=top+1;a++)
printf("%c",A[a]);
printf(""t"t");
}/*print*/
void print1()/*输出剩余串*/
{
int j;
for(j=0;j<b;j++)/*输出对齐符*/
printf(" ");
for(j=b;j<=l;j++)
printf("%c",B[j]);
printf(""t"t"t");
}/*print1*/
void main()
{
int m,n,k=0,flag=0,finish=0;
char ch,x;
type cha;/*用来接受C[m][n]*/
/*把文法产生式赋值结构体*/
e.origin='E';
strcpy(e.array,"TG");
e.length=2;
t.origin='T';
strcpy(t.array,"FS");
t.length=2;
g.origin='G';
strcpy(g.array,"+TG");
g.length=3;
g1.origin='G';
g1.array[0]='^';
g1.length=1;
s.origin='S';
strcpy(s.array,"*FS");
s.length=3;
s1.origin='S';
s1.array[0]='^';
s1.length=1;
f.origin='F';
strcpy(f.array,"(E)");
f.length=3;
f1.origin='F';
f1.array[0]='i';
f1.length=1;
for(m=0;m<=4;m++)/*初始化分析表*/
for(n=0;n<=5;n++)
C[m][n].origin='N';/*全部赋为空*/
/*填充分析表*/
C[0][0]=e;C[0][3]=e;
C[1][1]=g;C[1][4]=g1;C[1][5]=g1;
C[2][0]=t;C[2][3]=t;
C[3][1]=s1;C[3][2]=s;C[3][4]=C[3][5]=s1;
C[4][0]=f1;C[4][3]=f;
printf("提示:本程序只能对由'i','+','*','(',')'构成的以'#'结束的字符串进行分析,"n");
printf("请输入要分析的字符串:");
do/*读入分析串*/
{
scanf("%c",&ch);
if ((ch!='i') &&(ch!='+') &&(ch!='*')&&(ch!='(')&&(ch!=')')&&(ch!='#'))
{
printf("输入串中有非法字符"n");
exit(1);
}
B[j]=ch;
j++;
}while(ch!='#');
l=j;/*分析串长度*/
ch=B[0];/*当前分析字符*/
A[top]='#'; A[++top]='E';/*'#','E'进栈*/
printf("步骤"t"t分析栈 "t"t剩余字符 "t"t所用产生式 "n");
do
{
x=A[top--];/*x为当前栈顶字符*/
printf("%d",k++);
printf(""t"t");
for(j=0;j<=5;j++)/*判断是否为终结符*/
if(x==v1[j])
{
flag=1;
break;
}
if(flag==1)/*如果是终结符*/
{
if(x=='#')
{
finish=1;/*结束标记*/
printf("acc!"n");/*接受 */
getchar();
getchar();
exit(1);
}/*if*/
if(x==ch)
{
print();
print1();
printf("%c匹配"n",ch);
ch=B[++b];/*下一个输入字符*/
flag=0;/*恢复标记*/
}/*if*/
else/*出错处理*/
{
print();
print1();
printf("%c出错"n",ch);/*输出出错终结符*/
exit(1);
}/*else*/
}/*if*/
else/*非终结符处理*/
{
for(j=0;j<=4;j++)
if(x==v2[j])
{
m=j;/*行号*/
break;
}
for(j=0;j<=5;j++)
if(ch==v1[j])
{
n=j;/*列号*/
break;
}
cha=C[m][n];
if(cha.origin!='N')/*判断是否为空*/
{
print();
print1();
printf("%c->",cha.origin);/*输出产生式*/
for(j=0;j<cha.length;j++)
printf("%c",cha.array[j]);
printf(""n");
for(j=(cha.length-1);j =0;j--)/*产生式逆序入栈*/
A[++top]=cha.array[j];
if(A[top]=='^')/*为空则不进栈*/
top--;
}/*if*/
else/*出错处理*/
{
print();
print1();
printf("%c出错"n",x);/*输出出错非终结符*/
exit(1);
}/*else*/
}/*else*/
}while(finish==0);
}/*main*/
3、LR(1)
#include<stdio.h>
#include<string.h>
char *action[10][3]={"S3#","S4#",NULL, /*ACTION表*/
NULL,NULL,"acc",
"S6#","S7#",NULL,
"S3#","S4#",NULL,
"r3#","r3#",NULL,
NULL,NULL,"r1#",
"S6#","S7#",NULL,
NULL,NULL,"r3#",
"r2#","r2#",NULL,
NULL,NULL,"r2#"};
int goto1[10][2]={1,2, /*QOTO表*/
0,0,
0,5,
0,8,
0,0,
0,0,
0,9,
0,0,
0,0,
0,0};
char vt[3]={'a','b','#'}; /*存放非终结符*/
char vn[2]={'S','B'}; /*存放终结符*/
char *LR[4]={"E->S#","S->BB#","B->aB#","B->b#"};/*存放产生式*/
int a[10];
char b[10],c[10],c1;
int top1,top2,top3,top,m,n;
void main(){
int g,h,i,j,k,l,p,y,z,count;
char x,copy[10],copy1[10];
top1=0;top2=0;top3=0;top=0;
a[0]=0;y=a[0];b[0]='#';
count=0;z=0;
printf("请输入表达式"n");
do{
scanf("%c",&c1);
c[top3]=c1;
top3=top3+1;
}while(c1!='#');
printf("步骤"t状态栈"t"t符号栈"t"t输入串"t"tACTION"tGOTO"n");
do{
y=z;m=0;n=0; /*y,z指向状态栈栈顶*/
g=top;j=0;k=0;
x=c[top];
count++;
printf("%d"t",count);
while(m<=top1){ /*输出状态栈*/
printf("%d",a[m]);
m=m+1;
}
printf(""t"t");
while(n<=top2){ /*输出符号栈*/
printf("%c",b[n]);
n=n+1;
}
printf(""t"t");
while(g<=top3){ /*输出输入串*/
printf("%c",c[g]);
g=g+1;
}
printf(""t"t");
while(x!=vt[j]&&j<=2) j++;
if(j==2&&x!=vt[j]){
printf("error"n");
return;
}
if(action[y][j]==NULL){
printf("error"n");
return;
}
else
strcpy(copy,action[y][j]);
if(copy[0]=='S'){ /*处理移进*/
z=copy[1]-'0';
top1=top1+1;
top2=top2+1;
a[top1]=z;
b[top2]=x;
top=top+1;
i=0;
while(copy[i]!='#'){
printf("%c",copy[i]);
i++;
}
printf(""n");
}
if(copy[0]=='r'){ /*处理归约*/
i=0;
while(copy[i]!='#'){
printf("%c",copy[i]);
i++;
}
h=copy[1]-'0';
strcpy(copy1,LR[h]);
while(copy1[0]!=vn[k]) k++;
l=strlen(LR[h])-4;
top1=top1-l+1;
top2=top2-l+1;
y=a[top1-1];
p=goto1[y][k];
a[top1]=p;
b[top2]=copy1[0];
z=p;
printf(""t");
printf("%d"n",p);
}
}while(action[y][j]!="acc");
printf("acc"n");
}
4、逆波兰式
include<stdio.h>
#include<math.h>
#define max 100
char ex[max]; /*存储后缀表达式*/
void trans(){ /*将算术表达式转化为后缀表达式*/
char str[max]; /*存储原算术表达式*/
char stack[max]; /*作为栈使用*/
char ch;
int sum,i,j,t,top=0;
printf("*****************************************"n");
printf("*输入一个求值的表达式，以#结束。*"n");
printf("******************************************"n");
printf("算数表达式：");
i=0; /*获取用户输入的表达式*/
do{
i++;
scanf("%c",&str[i]);
}while(str[i]!='#' && i!=max);
sum=i;
t=1;i=1;
ch=str[i];i++;
while(ch!='#'){
switch(ch){
case '(': /*判定为左括号*/
top++;stack[top]=ch;
break;
case ')': /*判定为右括号*/
while(stack[top]!='('){
ex[t]=stack[top];top--;t++;
}
top--;
break;
case '+': /*判定为加减号*/
case '-':
while(top!=0&&stack[top]!='('){
ex[t]=stack[top];top--;t++;
}
top++;stack[top]=ch;
break;
case '*': /*判定为乘除号*/
case '/':
while(stack[top]=='*'||stack[top]=='/'){
ex[t]=stack[top];top--;t++;
}
top++;stack[top]=ch;
break;
case ' ':break;
default:while(ch>='0'&&ch<='9'){ /*判定为数字*/
ex[t]=ch;t++;
ch=str[i];i++;
}
i--;
ex[t]='#';t++;
}
ch=str[i];i++;
}
while(top!=0){
ex[t]=stack[top];t++;top--;
}
ex[t]='#';
printf(""n"t原来表达式：");
for(j=1;j<sum;j++)
printf("%c",str[j]);
printf(""n"t后缀表达式：",ex);
for(j=1;j<t;j++)
printf("%c",ex[j]);
}
void compvalue(){ /*计算后缀表达式的值*/
float stack[max],d; /*作为栈使用*/
char ch;
int t=1,top=0; /*t为ex下标，top为stack下标*/
ch=ex[t];t++;
while(ch!='#'){
switch(ch){
case '+':
stack[top-1]=stack[top-1]+stack[top];
top--;
break;
case '-':
stack[top-1]=stack[top-1]-stack[top];
top--;
break;
case '*':
stack[top-1]=stack[top-1]*stack[top];
top--;
break;
case '/':
if(stack[top]!=0)
stack[top-1]=stack[top-1]/stack[top];
else{
printf(""n"t除零错误!"n");
exit(0); /*异常退出*/
}
top--;
break;
default:
d=0;
while(ch>='0'&&ch<='9'){
d=10*d+ch-'0'; /*将数字字符转化为对应的数值*/
ch=ex[t];t++;
}
top++;
stack[top]=d;
}
ch=ex[t];t++;
}
printf(""n"t计算结果:%g"n",stack[top]);
}
main(){
trans();
compvalue();
}