比较两数的大小，计算小数依次加到大数的和

运行结果换行，只用了std：：endl； 实际看资料有“/r/n”，实际怎么用，没看出效果来。。。笨啊。。

#include <iostream>
int main ()
{
	int v1,v2,lower,upper ;
	std ::cout <<"enter two numbers:"<<std ::endl ;
	std ::cin >>v1 >> v2 ;
	if( v1 >v2 )
	{ lower =v2 ;upper =v1 ;}
	else { lower =v1  ;upper = v2 ;}
	int sum=0;
	for (int val =lower ;val <=upper ; val ++)
		sum += val ;
	std ::cout <<"the lower is "<<lower <<std ::endl ;
	std ::cout <<"the upper is " <<upper <<std ::endl ;
	std ::cout <<"the sum from "<<lower<<" to "<< upper <<" is " << sum << std ::endl ;
	system ("pause");
	return 0;
}