在输入的数字范围内求所有数总和，比较for语句，while语句，do—while语句的实现效果！！！(C++)

望采纳！！！ 

1.用for语句实现
#include<iostream>
using namespace std;
int main()
{
	int i, sum = 0,n;
	cin >> n;
	for (i = 1; i <= n; i++)
	{
		sum = sum + i;
	}
	cout << sum << endl;
	return 0;
}


2.用while语句实现
#include <iostream>
using namespace std;
int main()
{
	int i=1, sum = 0,n;
	cout << "请输入最大数字：" << endl;
	cin >> n;
	while (i <= n)
	{
		sum = sum + i;
			i++;
	}
	cout << sum << endl;
	return 0;
}


3.用do-while语句实现
#include <iostream>
using namespace std;
int main()
{
	int i=1, n, sum = 0;
	cout << "请输入最大数字" << endl;
	cin >> n;
	do {
		sum = sum + i;
		i++;
	} while (i <= n);
	cout << sum << endl;
	return 0;
}