HDUacm 1001 Sum Problem

problem description
    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
 
codes:
 1 #include <stdio.h>
 2 main()
 3 {
 4     int a,i,sum;
 5    
 6     while(scanf("%d",&a)!=eof)
 7     {
 8         sum=0;
 9         for(i=1;i<=a;i++)
10             sum=sum+i;
11         printf("%d\n\n",sum);
12     }
13 }
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 作者 任琦磊