hdu1001 sum problem

Hey, welcome to HDOJ(Hangzhou Dianzi University Online Judge).
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, followed by a blank line. You may assume the result will be in the range of 32-bit signed integer.

Sample Input
1
100

Sample Output
1
5050

基础题，很简单，代码如下所示：

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#include<stdio.h> 
using namespace std;
void (int a);
int main()
{
    int a;
    while(scanf(cin>>a)
   {
        sum(a);
        cout<<endl;
    }
}
void sum(int a)
{
    int s=0;
    for(int i=1;i<=a;i++)
 {
         s = s+i;
    }
    cout<<s<<endl;
}