词法分析

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#define Max 1000
int j=1;
long g=0;
char nchar[Max]={""}; 
int k=0;
char ch=NULL;
char m[30]={""};
int sym=-1;
main()
{
    char zfc;
    int n;
    printf("请输入一串字符串:");
    while((zfc=getchar())!='$')
    {
        nchar[g]=zfc;
        g++;
    } 
    do
    {
        n=getsym();
    }while(n); 
}
int getsym()
{
    int i;
    char a[2]={""};
    char word[][15]={"begin","do","end","if","then","while"};
    int wsym[6]={1,2,3,4,5,6};
    int ssym[9]={25,26,27,28,0,13,14,15,16};
    char b[9]={'=',';','(',')','#','+','-','*','/'};
    if(j==1&&k<g)
    {
        ch=nchar[k];
        j++;
        k++;
    }
    while(ch==' '||ch==10||ch==9||ch==13)
    {
        if(k==g)
        {
            return 0;
        }
        ch=nchar[k];
        k++;
    }

<字母> A->a|b|c|d|...|z

<数字> B->1|2...|9

<整数常数> S->C|SB C->1|2|3|...|9

<标识符> F->A|SB|SA|S

<关键字> S->begin|if|then|while|do|end

<运算符> S->+|-|*|%|=|#|<|<=|>|>=|:=

<界符> S->(|)|,|;|.