Question

c++编程，注意，用c++(cin，cout)

c++编程，注意，用c++(cin，cout)Description
In this problem, your task is to calculate SUM(n) = 1 + 2 + 3 + ... + n.

Input
The input will consist of a series of integers n, one integer per line.

Output
For each case, output SUM(n) in one line. You can assume the result will be in the range of 32-bit signed integer.

Process to the end of file.

Sample Input
1
100

Sample Output
1
5050

Answer 1

#include <string>
#include <iostream>
#include <sstream>
using namespace std;

int sum(int max)
{
int result = 0;
for(int i = 1; i <= max; ++i)
result += i;
return result;
}

int main()
{
string line;
while(getline(cin,line))
{
int num;
stringstream ss(line);
ss >> num;
cout << sum(num) << endl;
}
return 0;
}

====================================
./a.out << EOF
> 1
> 100
> EOF
================================
1
5050

追问

哥，不用这么复杂吧?

问一下输出的5050上边的那个1是怎么来的?

追答

你贴个精简的, 这也复杂啊...
输入 1 , 输出 sum(1)
输入 50, 输出 sum(50)