c++初学者碰到的问题~

#include<iostream.h>
void main()
{
int num=0;
cout<<"输入一个四位数：";
cin>>num;
cout<<endl;
cout<<"排列后的结果是："<<endl;
int elem[4];
elem[0]=(int)(num/1000);
elem[1]=(int)((num/100)-10*elem[0]);
elem[2]=(int)((num/10)-100*elem[0]-10*elem[1]);
elem[3]=(num%10);
int temp=elem[0];
for(int i=0;i<=3;i++)
{
for(int j=i;j<=3;j++)
{
if(elem[i]<=elem[j])
{
temp=elem[i];
elem[i]=elem[j];
elem[j]=temp;
}
else continue;
}
}
for(int k=0;k<=3;k++)
{
cout<<elem[k];
}
cout<<endl;
}

#include <iostream.h>

/************************************************************************
Make sure the "<" can be used between SomeType
*********************************************************