How a can I extract these three numbers fast?

I have an std::string which contains 3 numbers which are separated by spaces for instance: 123开发者_运维问答334 33335 54544. How a can I extract these three numbers fast?

int r = ... /* 123334 */
int g = ... /* 33335 */
int b = ... /* 54544*/

The easiest way is to use a stringstream:

std::string numbers = "123334 33335 54544";
std::istringstream parse(numbers);
int r, g, b;

parse >> r;
parse >> g;
parse >> b;

if (!parse)
   throw std::runtime_error("invalid string");

Create a stringstream object, assign to it your string, then use operator>> to read the 3 numbers.

An alternative solution would be.

std::string numbers = "123334 33335 54544";
std::istringstream iss(numbers);
std::vector<int> int_numbers;
std::transform(std::istream_iterator<std::string>(iss),
    std::istream_iterator<std::string>(),
    std::back_inserter<std::vector<int> >(int_numbers), 
    boost::lambda::bind(&boost::lexical_cast<int, std::string>, boost::lambda::_1)
    );

But then you need lambda and lexical cast from the boost library.