C++文件流操作

#include "stdafx.h"
#include <string>
#include <iostream>
#include <fstream>
#include <iomanip>
#include <cstdlib>
using namespace std;

void writeCharsetToFile(const string& filename);
void outputFile(const string& filename);

int _tmain(int argc, _TCHAR* argv[])
{
 writeCharsetToFile("charset.out");
 outputFile("charset.out");
 
 system("pause");
 return 0;
}

void writeCharsetToFile(const string& filename)
{
 //open output file
 ofstream file(filename.c_str());

 //file opened?
 if(!file){
  //No, abort program
  cerr<<"can't open output file/""<<filename<<"/""<<endl;
  exit(EXIT_FAILURE);
 }

 //write character set
 for(int i=32;i<256;i++)
 {
  file<<"value: "<<setw(3)<<i<<"  "
   <<"char: "<<static_cast<char>(i)<<endl;
 }
}//close file automatically

void outputFile(const string& filename)
{
 //open input file
 ifstream file(filename.c_str());

 //file opened?
 if(!file){
  //No,abort program
  cerr<<"can't open input file/""<<filename<<"/""<<endl;
  exit(EXIT_FAILURE);
 }

 //copy file contents to cout
 char c;
 while(file.get(c)) { cout.put(c);}
}//close file automatically