scanner.h
#include<iostream>
#include<fstream>
#include<string>
using namespace std; class Scanner{
private:
string infile;
string outfile;
string key[33];
string helpkey[33];
public:
Scanner(string infile_temp,string outfile_temp);
void readFile();
void getToken(string s,ofstream &out);
bool isLetter(char ch);
bool isDigit(char ch);
int reserve(const string& s); };
scanner.cpp
#include "scanner.h"
using namespace std;
Scanner:: Scanner(string infile_temp,string outfile_temp){
infile = infile_temp;
outfile = outfile_temp;
string key_temp[] = {"","auto","double","int","struct","break","else","long","switch",
"case", "enum","register","typedef","char","extern","return","union","const",
"float","short","unsigned","continue","for","signed","void","default","goto",
"sizeof","volatile","do","if","while","static"};
for(int i=;i<;i++){
key[i] = key_temp[i];
}
}
void Scanner::readFile(){
ifstream in(infile);
ofstream out(outfile);
string s;
while(getline(in,s)){
getToken(s,out);
}
}
//判断是否letter
bool Scanner::isLetter(char ch){
if((ch>=&&ch<=)||(ch>=&&ch<=)||ch==||ch==)
return true;
else
return false;
}
//判断是否数字
bool Scanner::isDigit(char ch){
if(ch>=&&ch<=)
return true;
else
return false;
}
//查找关键字
int Scanner::reserve(const string& s){
for(int i=;i<;i++)
if(s==key[i])
return i;
return ;
}
void Scanner::getToken(string s,ofstream &out){
size_t i=,code;
char ch;
string temp="";
ch=s[i];
while(i<s.length()){
//如果是空跳过
while(i<s.length()&&ch==' '){
i++;
ch=s[i];
}
//是字母
if(isLetter(ch)){
while((isLetter(ch)||isDigit(ch))&&i<s.length()){
temp+=ch;
i++;
ch=s[i];
}
i--;
code=reserve(temp);
if(code==){
out<<temp<<'\t'<<"标识符"<<endl;
temp="";
}else{
out<<temp<<'\t'<<"关键字"<<endl;
temp="";
}
}else if(isDigit(ch)){
while(isDigit(ch)){
temp+=ch;
i++;
ch=s[i];
}
i--;
out<<temp<<'\t'<<"常数"<<endl;
temp="";
}else if(ch=='='){
i++;
ch=s[i];
if(ch== '=' )
out<<"=="<<'\t'<<"判断相等"<<endl;
else{
i--;
out<<"="<<'\t'<<"赋值"<<endl;
}
}
else if(ch=='+'){
i++;
ch=s[i];
if(ch=='+')
out<<"++"<<'\t'<<"加1"<<endl;
else{
i--;
out<<"+"<<'\t'<<"加号"<<endl;
}
}
else if(ch=='&'){
i++;
ch=s[i];
if(ch=='&')
out<<"&&"<<'\t'<<"与"<<endl;
else{
i--;
out<<"&"<<'\t'<<"按位与"<<endl;
}
}
else if(ch=='|'){
i++;
ch=s[i];
if(ch=='|')
out<<"||"<<'\t'<<"或"<<endl;
else{
i--;
out<<"|"<<'\t'<<"按位或"<<endl;
}
}
else if(ch=='-')
out<<ch<<'\t'<<"减号"<<endl;
else if(ch==';')
out<<ch<<'\t'<<"分号"<<endl;
else if(ch=='(')
out<<ch<<'\t'<<"左括号"<<endl;
else if(ch==')')
out<<ch<<'\t'<<"右括号"<<endl;
else if(ch=='{')
out<<ch<<'\t'<<"左花括号"<<endl;
else if(ch=='}')
out<<ch<<'\t'<<"右花括号"<<endl;
else if(ch=='*'){
i++;
ch=s[i];
if(ch=='*')
out<<"**"<<'\t'<<"运算符"<<endl;
else{
i--;
out<<"*"<<'\t'<<"乘号"<<endl;
}
}
else if(ch=='<'){
i++;
ch=s[i];
if(ch=='=')
out<<"<="<<'\t'<<"小于等于"<<endl;
else{
i--;
out<<"<"<<'\t'<<"小于"<<endl;
}
}
else if(ch=='>'){
i++;
ch=s[i];
if(ch=='=')
out<<">="<<'\t'<<"大于"<<endl;
else{
i--;
out<<">"<<'\t'<<"小于"<<endl;
}
}
else
return ;
i++;
ch=s[i];
}
}