c++怎么输入token

问题是这样的

这个token该怎么输入呢
我不知道怎么写

（这行凑字数）

class Solution {
public:
    int evalRPN(vector<string> &tokens) {
        if(tokens.size() == 0)
            return 0;
        stack<int> result;
        for(auto token : tokens)
        {
            if(token == "+" || token == "-" || token == "*" || token == "/")
            {
                if(result.size() < 2)
                    return 0;
                int right = result.top();result.pop();
                int left = result.top();result.pop();
                int res = 0;
                if(token == "+")
                    res = left+right;
                else if(token == "-")
                    res = left-right;
                else if(token == "*")
                    res = left*right;
                else if(token == "/")
                    res = left/right;
                result.push(res);
            }
            else
            {
                stringstream ss;
                ss << token;
                int res;
                ss >> res;
                result.push(res);
                //result.push(atoi(token.c_str()));
            }
        }
        return result.top();
    }
};