0917 实验一 词法分析程序

#include <stdio.h>
#include <string.h>
#include <iostream.h>
#define BEGIN 1
#define IF 2
#define THEN 3
#define WHILE 4
#define DO 5
#define END 6
#define INT 11
#define LT 20
#define LE 21
#define EQ 24
#define NE 22
#define GT 12
#define GE 24
#define IS 18
#define PL 13
#define MI 14
#define MU 15
#define DI 16
#define SS 17
#define ID 10
#define AI  26
#define BI 27
#define HI 58
#define JI  0

char *keyword[8]={"begin","end","if","then","do","while"};
int i=0,j=0,k=0,t=0;
char ch,dck[20];
char * chr_form[100];
char * int_form[100];
char form[1000];
int q=0,temp;
void GetChar()
{
ch=form[k];
k++;
}
void getbc()
{
while(ch==' ')
{

GetChar();
}
}
void concat()
{
dck[i]=ch;
i++;
}
bool isletter()
{
if(((ch<='z')&&(ch>='a'))||((ch<='Z')&&(ch>='A')))
return(1);
else
return(0);
}
bool isdigit()
{
if(((ch)<='9')&&((ch)>='0'))
return (1);
else
return (0);
}
int reserve()
{
for(int q=0;q<5;q++)
{
if(strcmp(keyword[q],dck)==0)
return q;
if(q==4)
return -1;
}
}
void retract()
{
k--;
ch=NULL;
}
char *insertld()
{
chr_form[j]=dck;
j++;
return chr_form[0];
}
char * insertconst()
{
int_form[t]=dck;
t++;
return int_form[0];
}
int code;
void output(int a,char *p1,char *p2)
{
cout<<"\t种别码:"<<a<<"\t 单词值:";
while(p1<=p2)
{
printf("%s",*p1);
p1++;
}
cout<<endl;
}

void analyze()
{
GetChar();
getbc();
if(isletter())
{
while (isletter()||isdigit())
{
concat();
GetChar();
}
retract();
code=reserve();
switch(code)
{
case 0:cout<<"单词符号:" <<dck<<"  种别码为: "<<BEGIN<<endl;break;

case 1:cout<<"单词符号:" <<dck<<"  种别码为: "<<END<<endl;break;

case 2:cout<<"单词符号:" <<dck<<"  种别码为: "<<IF<<endl;break;

case 3:cout<<"单词符号:" <<dck<<"  种别码为: "<<THEN<<endl;break;
case 4:cout<<"单词符号:" <<dck<<"  种别码为: "<<DO<<endl;break;
case 5:cout<<"单词符号:" <<dck<<"  种别码为: "<<WHILE<<endl;break;

default:
cout<<"单词符号:" <<dck<<"  种别码为: "<<ID<<endl;break;

}
}
else
{
if( isdigit())
{
while(isdigit()||ch=='.')
{
concat();
GetChar();
}
retract();
cout<<"单词符号:"<<dck<<"  种别码为："<<INT<<endl;
}
else
{
switch(ch)
{
case'+': cout<<"单词符号:+  种别码为: "<<PL<<endl;break;
case'-': cout<<"单词符号:-  种别码为: "<<MI<<endl;break;
case'*': cout<<"单词符号:*  种别码为: "<<MU<<endl;break;
case'/': cout<<"单词符号:/  种别码为: "<<DI<<endl;break;
case';': cout<<"单词符号:;  种别码为: "<<AI<<endl;break;
case'(': cout<<"单词符号:(  种别码为: "<<BI<<endl;break;
case')': cout<<"单词符号:)  种别码为: "<<HI<<endl;break;
case'#': cout<<"单词符号:#  种别码为: "<<JI<<endl;break;

case':':GetChar();
if(ch=='=')
{
cout<<"单词符号::=  种别码为: "<<IS<<endl;break;
}
else
{
retract();
cout<<"单词符号::   种别码为: "<<SS<<endl;break;
}
case'=':cout<<"单词符号:=  种别码:"<<EQ<<endl; break;
case'>':GetChar();switch(ch)
{
case'=':cout<<"单词符号:>=  种别码:"<<GE<<endl;break;
default: retract;
cout<<"单词符号:=> 种别码:"<<GT<<endl;break;
}
case'<':GetChar();
switch(ch)
{
case'=':cout<<"单词符号:<=  种别码:"<<LE<<endl;break;
case'>':cout<<"单词符号:<>  种别码:"<<NE<<endl;break;
default: retract();
cout<<"单词符号:<  种别码:"<<LT<<endl;break;
}
}
}
}

while(k<q)
{
for(int p=0;p<50;p++)
dck[p]='\0';
i=0;
analyze();
}
}

void main ()
{
printf("输入一段程序，以^结束：");
form[0]=cin.get();
for(q=1;form[q-1]!='!!';q++)
{
form[q]=cin.get();
if(form[q]=='^')
{
printf("所输入的程序段为:");
printf("\n");
cout.write(form,q);
break;
}
}
cout<<endl;
analyze();

}