c13-13.cpp

这我们老师对是面向对象程序设计（清华大学出版社）一书制作的PPT

#include <fstream>
using namespace std;
void save_to_file()
{ofstream outfile("f2.dat");
 if(!outfile)
  {cerr<<"open f2.dat error!"<<endl;
   exit(1);
  }
 char c[80];
 cin.getline(c,80);
 for(int i=0;c[i];i++)
  if(c[i]>=65 && c[i]<=90||c[i]>=97 && c[i]<=122)
    {outfile.put(c[i]);
     cout<<c[i];}
 cout<<endl;
 outfile.close();
}

void get_from_file()
{char ch;
 ifstream infile("f2.dat",ios::in);
 if(!infile)
  {cerr<<"open f2.dat error!"<<endl;
   exit(1);
  }
 ofstream outfile("f3.dat");
 if(!outfile)
  {cerr<<"open f3.dat error!"<<endl;
   exit(1);
  }
 while(infile.get(ch))
  {if(ch>=97 && ch<=122)
     ch=ch-32;
   outfile.put(ch);
   cout<<ch;
  }
 cout<<endl;
 infile.close();
 outfile.close();
}
int main()
{save_to_file();
 get_from_file();
 return 0;
}