#include <iostream>
#include <vector>
#include <algorithm>
bool CompareFunction(std::string s1, std::string s2) {
if (s1.size() == s2.size()) {
return s1 < s2;
}
else {
return s1.size() < s2.size();
}
}
int main()
{
std::vector<std::string> v = {"7", "0", "55", "8", "9", "6"};
sort(v.begin(), v.end(), CompareFunction);
for(auto val: v) {
std::cout << val << " ";
}
}
/*
run:
0 6 7 8 9 55
*/