0909 初识编译原理

#include<stdio.h>
#include <string.h>
#include<iostream.h>
main(){
    char a[100];
    char ch,bh;
    int i,s;
    s=0;
    printf("请输入字符(输入#结束):");
    do
    {
         scanf("%c",&ch);
         a[s++]=ch;
    }while(ch!='#');
    for(i=0;i<s;i++)
    {
        bh=a[i];
        if(bh>='a'&&ch<='z')
        {
            if(a[i]=='b'&&a[i+1]=='e'&&a[i+2]=='g'&&a[i+3]=='i'&&a[i+4]=='n')
            {
                printf("<1,begin >\n");
            i=i+4;
            continue;
            }

            else if(a[i]=='i'&&a[i+1]=='f')
            {
                printf("<2,if >\n");
            i=i+1;
            continue;
            }

            else if(a[i]=='t'&&a[i+1]=='h'&&a[i+2]=='e'&&a[i+3]=='n')
            {
                printf("<3,then >\n");
            i=i+3;
            continue;
            }
            else if(a[i]=='w'&&a[i+1]=='h'&&a[i+2]=='i'&&a[i+3]=='l'&&a[i+4]=='e')
            {
                printf("<4,while >\n");
            i=i+4;
            continue;
            }
            else if(a[i]=='d'&&a[i+1]=='o')
            {
                printf("<5,do >\n");
            i=i+1;
            continue;
            }
            else if(a[i]=='e'&&a[i+1]=='n'&&a[i+2]=='d')
            {
                printf("<6,end >\n");
            i=i+2;
            continue;
            }
            else if(a[i]=='l'&&a[i+1]=='('&&a[i+2]=='l'&&a[i+3]=='|'&&a[i+4]=='d'&&a[i+5]==')'&&a[i+6]=='*')
            {
                printf("<10,l(l|d)* >\n");
            i=i+6;
            continue;
            }
            else if(a[i]=='d'&&a[i+1]=='d'&&a[i+2]=='*')
            {
                printf("<11,dd* >\n");
            i=i+2;
            continue;
            }
        }

        if(bh==':')
            if(a[i+1]=='='){
                printf("<18,:= >\n");
                i=i+1;
                continue;}
         if(bh=='<')
            if(a[i+1]=='='){
                printf("<21,<= >\n");
                i=i+1;
                continue;}
         if(bh=='<')
            if(a[i+1]=='>'){
                printf("<22,<> >\n");
                i=i+1;
                continue;}
         if(bh=='>')
            if(a[i+1]=='='){
                printf("<24,>= >\n");
                i=i+1;
                continue;}
        switch(bh)
        {
        case '+':
            printf("<13,%c >\n",bh);
            break;
         case '-':
            printf("<14,%c >\n",bh);
            break;
         case '*':
            printf("<15,%c >\n",bh);
            break;
         case '/':
            printf("<16,%c >\n",bh);
            break;
         case ':':
            printf("<17,%c >\n",bh);
            break;
         case '(':
            printf("<27,%c >\n",bh);
            break;
         case ')':
            printf("<28,%c >\n",bh);
            break;
         case '#':
            printf("<0,%c >\n",bh);
            break;
         case '>':
            printf("<23,%c >\n",bh);
            break;
         case '<':
            printf("<20,%c >\n",bh);
            break;
         case ';':
            printf("<26,%c >\n",bh);
            break;
        }
    }

}

结果：