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<<"	种别码:"<<a<<"	 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]='';
        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("
");
            cout.write(form,q);
            break;
        }
    }
    cout<<endl;
    analyze();

}