第7章 第4题

#include<iostream>
#include<fstream>
#include<cstdlib>
using namespace std;

void fun1()
{
int a[10];
ofstream outfile1("f1.dat"),outfile2("f2.dat");
if(!outfile1){
cerr<<"open f1.dat error!"<<endl;
exit(1);
}
if(!outfile2){
cerr<<"open f2.dat error!"<<endl;
exit(1);
}
cout<<"enter 10 integer numbers:";
for(int i=0;i<10;i++){
cin>>a[i];
outfile1<<a[i]<<" ";
}
cout<<"enter 10 integer numbers:";
for(int i=0;i<10;i++){
cin>>a[i];
outfile2<<a[i]<<" ";
}
outfile1.close();
outfile2.close();
}

void fun2()
{
ifstream infile("f1.dat");
if(!infile){
cerr<<"open f1.dat error!"<<endl;
exit(1);
}
ofstream outfile("f2.dat",ios::app);
if(!outfile){
cerr<<"open f2.dat 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.dat");
if(!infile){
cerr<<"open f2.dat error!"<<endl;
exit(1);
}
int a[20];
int i,j,t;
for(i=0;i<20;i++)
infile>>a[i];
for(i=0;i<19;i++)
for(j=0;j<19-i;j++)
if(a[j]>a[j+1]){
t=a[j];a[j]=a[j+1];a[j+1]=t;
}
infile.close();
ofstream outfile("f2.dat",ios::out);
if(!outfile){
cerr<<"open f2.dat error!"<<endl;
exit(1);
}
cout<<"data in f2.dat:"<<endl;
for(i=0;i<20;i++){
outfile<<a[i]<<" ";
cout<<a[i]<<" ";
}
cout<<endl;
outfile.close();
}

int main()
{
fun1();
fun2();
fun3();
return 0;
}