每日一题C++版（统计字符个数）

#include <iostream>
#include <string>
#include <vector>
using namespace std;
class Solution
{
public:
  Solution();
  Solution(string str_): str(str_){};
  int numberChar()
  {
    int ch[128] = {0};
    for (auto i = str.cbegin(); i != str.cend(); i++)
    {
        ch[int(*i)] = 1;
    }
    int number=0;
    for (int i = 0; i < 127; i++)
    {
      number = number + ch[i];
    }
    return number;
  }

private:
  string str;
};

int main()
{
  string str;
  cin >> str;
  Solution solution(str);
  cout << solution.numberChar() << endl;
  return 0;
}