对了，说明一下，要C语言版的

望能对你有些帮助!


词法分析:
#include <iostream.h>
#include <stdio.h>
#include <string.h>
FILE *f;
void noblank(char &ch)
{
    while (ch==' '||ch=='\n')
        ch=fgetc(f);
}
//====================================================================
void identifier(char name[],char &ch)
{
    int i;
    for (i=0;i<10;i++)
        name[i]='\0';
    i=0;
    name[i]=ch;i++;
    ch=fgetc(f);
    while (('0'<=ch&&ch<='9')||('a'<=ch&&ch<='z')||('A'<=ch&&ch<='Z'))
    {
        name[i]=ch;
        i++;
        ch=fgetc(f);
    }
}
//====================================================================
int intconst(char &ch)
{
    int num=0;
    while ('0'<=ch&&ch<='9')
    {
        num=num*10+(ch-'0');
        ch=fgetc(f);
    }
    return num;
}
//====================================================================
void main()
{
    char ch,name[20];
    char st1[10]={"#include"};
    char st2[10]={"main()"};
    char st3[10]={"{"};
    char st4[10]={"int"};
    char st5[10]={"}"};
    char st6[20]={"cout<<"};
    int num;
    f=fopen("prog.txt","r");
    if (f==NULL)
        cout<<"no such file."<<endl;
    ch=fgetc(f);
    while (!feof(f))
    {
        noblank(ch);
        if ((ch>='a'&&ch<='z')||(ch>='A'&&ch<='Z'))
        {
            identifier(name,ch);
            if (!strcmp(name,st1))  printf("${\n");
            else if (!strcmp(name,st2))  printf("$}\n");
            else if (!strcmp(name,st3))  printf("$int\n");
            else if (!strcmp(name,st4))  printf("$cout<<\n");
            else if (!strcmp(name,st5))  printf("$#include\n");
            else printf("$id,%s\n",name);
        }
        else if (ch>='0'&&ch<='9')
        {
            num=intconst(ch);
            printf("$intc,%d\n",num);
        }
        else switch(ch)
        {
            case'(':cout<<"lparen"<<endl;
                ch=fgetc(f);break;
            case')':cout<<"rparen"<<endl;
                ch=fgetc(f);break;
            case'+':cout<<"plus"<<endl;
                ch=fgetc(f);break;
            case'*':cout<<"mult"<<endl;
                ch=fgetc(f);break;
            case';':cout<<"semi"<<endl;
                ch=fgetc(f);break;
            case'=':cout<<"give value"<<endl;
                ch=fgetc(f);break;
            case'.':cout<<"point"<<endl;
                ch=fgetc(f);break;
            default:break;
        }
    }fclose(f);
}

我的
#define BEGIN 1
#define END   2
#define IF    3
#define THEN  4
#define ELSE  5
#define ID    6
#define INT   7
#define LT    8
#define LE    9
#define EQ    10
#define NE    11
#define GT    12
#define GE    13
#define TOKEN_SIZE 64
#define TAB_SIZE   5
#include<stdio.h>
#include<ctype.h>
#include<stdlib.h>
#include<string.h>
char TOKEN[TOKEN_SIZE];
extern int lookup(char *);
extern void  out(int ,char*);
extern void  report_error();
char ch;
//信息表
typedef struct{
int ad;
char id[6];
}info_ele;
info_ele info_tab[TAB_SIZE]={{1,"begin"},{2,"end"},{3,"if"},{4,"then"},{5,"else"}};
//扫描器函数
void scaner(FILE *fp)
{
    int i,c_id;
    ch=fgetc(fp);
    if(isalpha(ch)){
         TOKEN[0]=ch;
         i=1;
         ch=fgetc(fp);
         while(isalnum(ch))
            {TOKEN[i]=ch;
             i++;
             ch=fgetc(fp);
            }
         fseek(fp,-1,1);
         TOKEN[i]='\0';
         c_id=lookup(TOKEN);
         if (c_id==0) out(ID,TOKEN);
          else out(c_id,TOKEN);
          }
     else if(isdigit(ch)){
                TOKEN[0]=ch;
                i=1;
                ch=fgetc(fp);
                while(isdigit(ch))
                {TOKEN[i]=ch;
                  i++;
                  ch=fgetc(fp);
                }
                 fseek(fp,-1,1);
                TOKEN[i]='\0';
                out(INT,TOKEN);
          }
          else
              if(ch==' ');//遇见空格继续
              else switch(ch)
            {
                case '=':out(EQ,"=");
                           break;
                case '>':ch=fgetc(fp);
                            if(ch=='=')out(GE,">=");
                            else{ fseek(fp,-1,1);
                                     out(GT,">");
                            }
                            break;
                case'<':ch=fgetc(fp);
                          if(ch=='=') out(LE,"<=");
                          else if(ch=='>')out(NE,"<>");
                                 else{
                                       fseek(fp,-1,1);
                                       out(LT,"<");
                                 }
                            break;
                default: report_error();
                         break;
            }
}
                                 
int lookup(char p[])
{
    int i=0;
    for(i;i<TAB_SIZE;i++)
    {
        if(!strcmp(info_tab[i].id,p))return (info_tab[i].ad);
    }
     return 0;
    
}

void out(int a,char *p)
{
    
    switch(a){
    case BEGIN: printf("(BEGIN,%s)",p);break;
    case END : printf("(END,%s)",p); break;
    case IF: printf("(IF,%s)",p);break;
    case THEN: printf("(THEN,%s)",p);break;
    case ELSE: printf("(ELSE,%s)",p);break;
    case ID: printf("(ID,%s)",p);break;
    case INT:printf("(INT,%s)",p);break;
    case LT:printf("(LT,%s)",p);break;
    case LE:printf("(LE,%s)",p);break;
    case EQ:printf("(EQ,%s)",p);break;
    case NE:printf("(NE,%s)",p);break;
    case GT:printf("(GT,%s)",p);break;
    case GE:printf("(GE,%s)",p);break;
    default:   break;
    }
}

void report_error()
{
    printf("\n有错误！\n");
    exit(0);
}

---------------------------------
#include<stdio.h>
#include<stdlib.h>
extern void scaner(FILE *);
void  main()
{
extern char ch;
char fname[20];
FILE * fp;
printf("Enter file's name:");
scanf("%s",&fname);
if((fp=fopen(fname,"r"))==NULL)
{
  printf("\nfile open error!\n");
  exit(0);
}


do{scaner(fp);}while(ch!=EOF);
}

哇,好尽业``!![em11]