新手求助

#include <iostream>
#include <cctype>
#include <iomanip>
#include <string>
using namespace std;
int main()
{
int n = 0;
cin >> n;
for (int i = 0; i < n; i++)
{
string str;
int flag = 0;
int count[4] = { 0 };
double sum = 0;
cin >> str;
for (int i = 0; i < str.size(); i++)
{
if (isalpha(str[i]))
{
switch (str[i])
{
case 'C':
flag = 0;
break;
case 'H':
flag = 1;
break;
case 'O':
flag = 2;
break;
case 'N':
flag = 3;
break;
}
if (isalpha(str[i + 1]) || str[i + 1] == '\0')
{
count[flag]++;
}
}
else
{
if (!isalpha(str[i + 1]) && i + 1 != str.size())
{
count[flag] = count[flag] * 10 + (str[i] - '0')*10;
}
else
{
count[flag] += str[i] - '0';
}
}
}
sum = count[0] * 12.01 + count[1] * 1.008 + count[2] * 16.00 + count[3] * 14.01;
cout << fixed << setprecision(3) << sum << endl;
}
return 0;
}

count[flag] = count[flag] * 10 + (str[i] - '0') * 10;
这显然不对，怎么能直接*10呢