The output is not getting written into res.txt file

#include<iostream>
#include<fstream>
#include<cstdlib>
#include<stdio.h>
#include<process.h>
using namespace std;

void wr_thread(void *pParams)
{
    std::ofstream ot("test.txt");
    for(int i=0;i<10;i++)
        ot<<i<<"\n";
}
void  rd_thread(void *pParams)
{
     char * buffer;
     long size;
     std::ofstream res("res.txt");
     srd::ifstream rd("test.txt");
     int n;
     rd.open("test.txt");
     rd>>n;
     rd.seekg(0,ifstream::end);
     size=rd.tellg();
     rd.seekg(0);

     buffer = new char [size];
     if(!rd)
     {
         cout<<"error\n";
         exit(1);
     }
     else
     {
         rd.read (buffer,size);
         res.write(buffer,size);
     }
     delete []buffer;

     res.close();
     rd.close();
}
int main()
{
     _beginthread(wr_thread, 0, NULL );
     _beginthread(rd_thread, 0, NULL );
     cin>>ip;
     return(0);
}