#include <vector>
#include <string>
 
std::vector<std::string> DIFSplitStringByNumber(const std::string & str, int len)
{
    std::vector<std::string> entries;
    for(std::string::const_iterator it(str.begin()); it != str.end();)
    {
        int nbChar = std::min(len,(int)std::distance(it,str.end()));
        entries.push_back(std::string(it,it+nbChar));
        it=it+nbChar;
    };
    return entries;
}
 
#include <iostream>
int main() {
    for (auto str : DIFSplitStringByNumber("hello", 2)) {
      std::cout << str << std::endl;
    }
    return 0;
}

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