parse string to vector of int

You can use std::stringstream. You will need to #include <sstream> apart from other includes.

#include <sstream>
#include <vector>
#include <string>

std::string myString = "10 15 20 23";
std::stringstream iss( myString );

int number;
std::vector<int> myNumbers;
while ( iss >> number )
  myNumbers.push_back( number );

std::string myString = "10 15 20 23";
std::istringstream is( myString );
std::vector<int> myNumbers( ( std::istream_iterator<int>( is ) ), ( std::istream_iterator<int>() ) );

Or instead of the last line if the vector was already defined then

myNumbers.assign( std::istream_iterator<int>( is ), std::istream_iterator<int>() );