SDUT-编译原理-小codeblocks

 

#include<bits/stdc++.h>
#include<list>
using namespace std;
string str;
char line;
string num;
string s;
int flag =0;

string key[]= {"main","if","else","for","while","int"};

int main()
{
    while(cin.get(line))
    {
        str+=line;
    }
    for(int i=0; i<=str.size(); i++)
    {
        //运算符： = + - * / < <= > >= == !=
        //判断加减乘除
        if(str[i]=='+'||str[i]=='-'||str[i]=='*'||str[i]=='/')
            cout<<'('<<"operator"<<","<<str[i]<<')'<<endl;
        //判断比较符
        if(str[i]=='='||str[i]=='>'||str[i]=='<'||str[i]=='!')
        {
            if(str[i+1]=='=')
            {
                cout<<'('<<"operator"<<","<<str[i]<<str[i+1]<<')'<<endl;
                i++;
            }
            else
                cout<<'('<<"operator"<<","<<str[i]<<')'<<endl;
        }
        //界符boundary  { } ( ) , ;
        if(str[i]=='{'||str[i]=='}'||str[i]=='('||str[i]==')'||str[i]==','||str[i]==';')
        {
            cout<<'('<<"boundary"<<","<<str[i]<<')'<<endl;
        }
        //判断整数
        if(str[i]>='0'&&str[i]<='9')
        {
            while(str[i]>='0'&&str[i]<='9')
            {
                num+=str[i];
                i++;
            }
            i--;
            cout<<'('<<"integer"<<","<<num<<')'<<endl;
            num="";
        }
        //当以字母开头
        if((str[i]<='Z'&&str[i]>='A')||(str[i]<='z'&&str[i]>='a'))
        {
            while((str[i]<='Z'&&str[i]>='A')||(str[i]<='z'&&str[i]>='a')||(str[i]<='9'&&str[i]>='0'))
            {
                s+=str[i];
                i++;
            }
            for(int j=0; j<=5; j++)
            {
                if(key[j]==s)//判断是否是关键字
                {
                    flag =1;
                }
            }
            if(flag==1)
                cout<<'('<<"keyword"<<","<<s<<')'<<endl;
            else if(flag==0)
                cout<<'('<<"identifier"<<","<<s<<')'<<endl;
            s="";
            i--;
            flag=0;
        }
    }
}

 

 

//判断比较符