calculate SUM(n) = 1 + 2 + 3 + ... + n

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

C++统计字符个数

C++输入字符串，统计字符串中各种字符的个数，并输出，代码中已经给出相关例子