用Java（C++）做一个词法分析器，急用！！！
各位大侠，谁能用Java或者C++帮小弟做一个词法简单的分析器，急用，谢谢了！
[解决办法]
《编译原理》的题目吧，还是自个弄吧
如果是实际项目，可以用antlr，现成的词法、语法解析工具
[解决办法]
#include <iostream>
#include <ctype.h>
#include <fstream>
#include <string.h>
#include <malloc.h>
using namespace std;
ifstream fp("example.c",ios::in);
char cbuffer;
char *key[14]={"if","else","for","while","do","return","break","continue","int","void"
,"main","const","printf","char"}; //关键字
char *border[10]={ "," , ";" , "{" , "}" , "(" , ")" ,"//","\"","[","]"}; //分界符
char *arithmetic[6]={"+" , "-" , "*" , "/" , "++" , "--"}; //运算符
char *relation[7]={"<" , "<=" , "=" , ">" , ">=" , "==" ,"!="}; //关系运算符
char *lableconst[80]; //标识符
int lableconstnum=0; //统计常数和标识符数量
int constnum=40;
int linenum=1;
int search(char searchchar[],int wordtype)
{
int i=0,t=0;
switch (wordtype)
{
case 1:
{ for (i=0;i<=13;i++) //关键字
{
if (strcmp(key[i],searchchar)==0)
return(i+1);
}
return(0);}
case 2:
{
for (i=0;i<=9;i++) //分界符
{
if (strcmp(border[i],searchchar)==0)
return(i+1);
}
return(0);
}
case 3:
{
for (i=0;i<=5;i++) //运算符
{
if (strcmp(arithmetic[i],searchchar)==0)
return(i+1);
}
return(0);
}
case 4:
{
for (i=0;i<=6;i++) //关系运算符
{
if (strcmp(relation[i],searchchar)==0)
return(i+1);
}
return(0);
}
case 5:
{
for (t=40;t<=constnum;t++) //常数
{
if (strcmp(searchchar,lableconst[t])==0)//判断该常数是否已出现过
return(t+1);
}
lableconst[t-1]=(char *)malloc(sizeof(searchchar));//为新的元素分配内存空间
strcpy(lableconst[t-1],searchchar);//为数组赋值lableconst指针数组名
constnum++; //常数个数自加
return(t);
}
case 6:
{
for (i=0;i<=lableconstnum;i++)
{
if (strcmp(searchchar,lableconst[i])==0) //判断标识符是否已出现过
return(i+1);
}
lableconst[i-1]=(char *)malloc(sizeof(searchchar));
strcpy(lableconst[i-1],searchchar);
lableconstnum++; //标识符个数自加
return(i);
}
default:cout<<"错误！";
}
}
char alphaprocess(char buffer) //字符处理过程
{
int atype;
int i=-1;
char alphatp[20];
while ((isalpha(buffer))||(isdigit(buffer))) //这两个函数分别是判字符和判数字函数
{
alphatp[++i]=buffer;
fp.get(buffer);
}
alphatp[i+1]='\0';//在末尾添加字符串结束标志
if (atype=search(alphatp,1))
cout<<"linenum: "<<linenum<<" String= "<<alphatp<<"\t\t\t"<<"关键字"<<endl;
else
{
atype=search(alphatp,6); //标识符
cout<<"linenum: "<<linenum<<" String= "<<alphatp<<"\t\t\t"<<"标识符"<<endl;
}
return(buffer);
}
char digitprocess(char buffer) //数字处理过程
{
int i=-1;
char digittp[20];
int dtype;
while ((isdigit(buffer)))
{
digittp[++i]=buffer;
fp.get(buffer);
}
digittp[i+1]='\0';
dtype=search(digittp,5);
cout<<"linenum: "<<linenum<<" String= "<<digittp<<"\t\t\t"<<"数据"<<endl;
return(buffer);
}
char otherprocess(char buffer) //分界符、运算符、逻辑运算符、等
{
int i=-1;
char othertp[20];
int otype,otypetp;
othertp[0]=buffer;
othertp[1]='\0';
if (otype=search(othertp,3))
{
fp.get(buffer);
othertp[1]=buffer;
othertp[2]='\0';
if (otypetp=search(othertp,3)) //判断该运算符是否是
//由连续的两个字符组成的
{
cout<<"linenum: "<<linenum<<" String= "<<othertp<<"\t\t\t"<<"运算符"<<endl;
fp.get(buffer);
return(buffer);
}
else //单字符逻辑运算符
{
othertp[1]='\0';
cout<<"linenum: "<<linenum<<" String= "<<othertp<<"\t\t\t"<<"逻辑运算符"<<endl;
return(buffer);
}
}
if (otype=search(othertp,4)) //关系运算符
{
fp.get(buffer);
othertp[1]=buffer;
othertp[2]='\0';
if (otypetp=search(othertp,4)) //判断该关系运算符是否是
//由连续的两个字符组成的
{
cout<<"linenum: "<<linenum<<" String= "<<othertp<<"\t\t\t"<<"关系运算符"<<endl;
fp.get(buffer);
return(buffer);
}
else //单字符逻辑运算符
{
othertp[1]='\0';
cout<<"linenum: "<<linenum<<" String= "<<othertp<<"\t\t\t"<<"逻辑运算"<<endl;
return(buffer);
}
}
if (buffer=='!') //"=="的判断
{
fp.get(buffer);
if (buffer=='=')
//cout<<"!= (2,2)\n";
fp.get(buffer);
return(buffer);
}
else
{
if (otype=search(othertp,2)) //分界符
{
cout<<"linenum: "<<linenum<<" String= "<<othertp<<"\t\t\t"<<"分界符"<<endl;
fp.get(buffer);
return(buffer);
}
}
if ((buffer!='\n')&&(buffer!=' '))
cout<<"错误！,字符非法"<<"\t\t\t"<<buffer<<endl;
fp.get(buffer);
return(buffer);
}
int main()
{
int i;
for (i=0;i<=50;i++)
{
lableconst[i]=" ";//用于保存标识符
}
if (!fp){
cout<<"文件打开失败,请确认文件信息!!!"<<endl;
return 0;
}
else
{
fp.get (cbuffer);
while (!fp.eof())
{
if(cbuffer=='\n')
{
linenum++;
fp.get(cbuffer);
}
else if (isalpha(cbuffer))
{
cbuffer=alphaprocess(cbuffer);
}
else if (isdigit(cbuffer))
{
cbuffer=digitprocess(cbuffer);
}
else
cbuffer=otherprocess(cbuffer);
}
}
cout<<"标识符个数是:"<<lableconstnum<<"分别是"<<endl;
i=0;
while(i<lableconstnum)
{
cout<<lableconst[i++]<<" ";
}
cout<<endl;
cout<<"完成\n";
getchar();
return 0;
}
这是我们编译原理课上的实验程序，你自己改一下吧，其实自己做也可以做出来的
[解决办法]
楼主自己看着办，按照思路可以继续完善的。
