cpp string find all occurence

1#include <string>
2#include <iostream>
3
4using namespace std;
5
6int main()
7{
8    string s("hello hello");
9    int count = 0;
10    size_t nPos = s.find("hello", 0); // first occurrence
11    while(nPos != string::npos)
12    {
13        count++;
14        nPos = s.find("hello", nPos + 1);
15    }
16
17    cout << count;
18};

1string str,sub; // str is string to search, sub is the substring to search for
2
3vector<size_t> positions; // holds all the positions that sub occurs within str
4
5size_t pos = str.find(sub, 0);
6while(pos != string::npos)
7{
8    positions.push_back(pos);
9    pos = str.find(sub,pos+1);
10}
11