How do you search a std::string for a substring in C++?

Question

I'm trying to parse a simple string in C++. I know the string contains some text with a colon, followed immediately by a space, then a number. I'd like to extract just the number part of the string. I can't just tokenize on the space (using sstream and <<) because the text in front of the colon may or may not have spaces in it.

Some example strings might be:

Total disk space: 9852465

Free disk space: 6243863

Sectors: 4095

I'd like to use the standard library, but if you have another solution you can post that too, since others with the same question might like to see different solutions.

Answer 1

std::string strInput = "Total disk space: 9852465";
std::string strNumber = "0";
size_t iIndex = strInput.rfind(": ");
if(iIndex != std::string::npos && strInput.length() >= 2)
{
  strNumber = strInput.substr(iIndex + 2, strInput.length() - iIndex - 2)
}