c++初学者求助！！！非求作业！！！

作用是反转列表。。。
#include <iostream>
#include <list>
#include <algorithm>
#include <string.h>
#include <fstream>
using namespace std;
int main()
{
   ifstream input("input.txt");
   ofstream output("output.txt");
   if(!input)
    {
      cout<<"input.txt open error"<<endl;
      exit(0);
    }
    if(!output)
    {
    cout<<"output.txt open error"<<endl;
    exit(0);
    }
    list<int> p;
    list<int>::iterator q;
    char one_line[1000];
    char *number;
    while(!input.eof())
    {
     input.getline(one_line,1000);
     number=strtok(one_line,",");
     while(number!=NULL)
     {
        p.push_back(atoi(number));
        number=strtok(NULL,",");
     }
     reverse(p.begin(),p.end());
     for(q=p.begin();q!=p.end();q++)
     {
         if(q!=p.begin())
            output<<",";
         output<<*q;
     }
     output<<endl;
    }
    input.close();
    output.close();
    return 0;
}

input.txt内容如下：
2,3,4,2,4,5,2,4,7
56,34,22,45,222
23,22,323,322
output.txt内容如下：
7,4,2,5,4,2,4,3,2
222,45,22,34,56,2,3,4,2,4,5,2,4,7
322,323,22,23,7,4,2,5,4,2,4,3,2,56,34,22,45,222


求高手教我！！！