betweensum.cpp

C++ primer plus第五章编程练习的代码

#include <iostream>

int main()
{
	using namespace std;
	int lower;
	int upper;
	cout<<"Please input the lower:";
	cin>>lower;
	cout<<"Please input the upper:";
	cin>>upper;
	while(lower>upper)
	{
		cout<<"lower have to less than upper!please input again…"<<endl;
		cout<<"Please input the lower:";
		cin>>lower;
		cout<<"Please input the upper:";
		cin>>upper;
	}
	int sum=0;
	for(;lower<=upper;lower++)
	{	
		sum+=lower;
	}
	cout<<"result is:"<<sum<<endl;
	system("Pause");
	return 0;
}