7-4

#include <iostream>
#include <fstream>
using namespace std;
void fun1()
{
 int a[10];
 ofstream outfile1("f1.data",ios::out),outfile2("f2.data",ios::out);
 if(!outfile1)
 {
  cerr<<"open error!"<<endl;
  exit(1);
 }
 if(!outfile2)
 {
  cerr<<"open error!"<<endl;
  exit(1);
 }
 cout<<"input 10 integer numbers:"<<endl;
 for(int i=0;i<10;i++)
 {
  cin>>a[i];
  outfile1<<a[i]<<" ";
 }
 cout<<"input 10 integer numbers:"<<endl;
 for(i=0;i<10;i++)
 {
  cin>>a[i];
  outfile2<<a[i]<<" ";
 }
 outfile1.close();
 outfile2.close();
}
void fun2()
{
 ifstream infile("f1.data");
 if(!infile)
 {
	cerr<<"open error!"<<endl;
    exit(1);
 }
 ofstream outfile("f2.data",ios::app);
 if(!outfile)
 {
    cerr<<"open error!"<<endl;
	exit(1);
 }
 int a;
 for(int i=0;i<10;i++)
 {
  infile>>a;
  outfile<<a<<" ";
 }
 infile.close();
 outfile.close();
}
void fun3()
{
 ifstream infile("f2.data");
 if(!infile)
 {
  cerr<<"open error!"<<endl;
  exit(1);
 }
 int a[20];
 int i,j,t;
 for(i=0;i<20;i++)
	 infile>>a[i];
 for(i=0;i<20;i++)
	 for(j=i+1;j<20;j++)
		 if(a[i]>a[j])
		 {t=a[i];a[i]=a[j];a[j]=t;}
 infile.close();
 ofstream outfile("f2.data",ios::out);
 if(!outfile)
 {
   cerr<<"open error!"<<endl;
	   exit(1);
 }
 cout<<"data in f2.data:"<<endl;
 for(i=0;i<20;i++)
 {
  outfile<<a[i]<<" ";
  cout<<a[i]<<" ";
 }
 cout<<endl;
 outfile.close();
}
int main()
{
 fun1();
 fun2();
 fun3();
 return 0;
}