Требуется построчно объяснить программу, заранее благодарен.

[drun9ruz]

#include "stdafx.h"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <sys\stat.h>
#include <io.h>
using namespace std;
int main(void){
	setlocale(LC_ALL, "rus");
	                                                 
	int handle,bytes;
	
	if ((handle = _open("C:\\RXX\\TEST.txt", O_CREAT | O_TEXT| O_RDWR, S_IWRITE | S_IREAD)) == -1)       // открываем файл
	{
		perror("Error:");
		getchar();
		return 1;
	}
	else {
		
		 long longFile = _lseek(handle,0,SEEK_END);                  
   _lseek(handle,0,SEEK_SET);
   unsigned char* buf = (unsigned char*)malloc(longFile+1);
   
   if ((bytes = _read(handle, buf, longFile)) == -1) {
      printf("Read Failed.\n");
	  free(buf);
	  getchar();
      exit(1);
   }
   else {
      printf("Read: %d bytes read.\n", bytes);
 buf[longFile]='\0';
      cout<<buf;
	cout<<"\n";
   }
	char* msg=(char*)buf;
	for (int i=0; i<strlen(msg); i++)
	{ 
		if ((unsigned char)msg[i]>= 224 && (unsigned char)msg[i]<= 255)
		{msg[i]=(char)((unsigned char)msg[i] - 32 ) ;
	 }
		
	}
	cout << "\n"<< buf;
	_lseek (handle, 0, SEEK_SET);

	if ((handle = _open("C:\\RXX\\TEST5.txt", O_CREAT | O_TEXT| O_RDWR, S_IWRITE | S_IREAD)) == -1)  
	{
		perror("Error:");
		getchar();
		return 1;
	}
	else {
		_write(handle, buf, bytes);
	}
	getchar();
	return 0;
   }
}