is a ++ before a container the same as moving the index by one?

Question

I am unfamiliar with this syntax: ++fCount[index]. Where list is another vector.

I was thinking it was the same as below, but its not:

int i = 0;
vector<int> fCount(1001,0);
for(auto index : list)
{
    fCount[i] = index;
    i++;
}

piece of code:

vector<int> fCount(1001,0);
for(auto index : list)
{
    ++fCount[index];
}