Divide a String Into Groups of Size k

<-E 2138> Divide a String Into Groups of Size k

class Solution {
public:
    vector<string> divideString(string s, int k, char fill) {

        while(s.size() % k != 0)
            s += fill;

        vector<string> v;
        string sub;

        for(int i = 0; i < s.size(); i = i + k) {
            sub = "";
            sub = s.substr(i,k);
            v.push_back(sub);
        }
        return v;
    }
};