std::match_results<BidirIt,Alloc>::position (3) - Linux Manuals

std::match_results<BidirIt,Alloc>::position: std::match_results<BidirIt,Alloc>::position

NAME

std::match_results<BidirIt,Alloc>::position - std::match_results<BidirIt,Alloc>::position

Synopsis

difference_type position( size_type n = 0 ) const; (since C++11)

Returns the position of the first character of the specified sub-match.
If n == 0, the position of the first character of the entire matched expression is returned.
If n > 0 && n < size(), the position of the first character of the nth sub-match is returned.
if n >= size(), a position of the first character of the unmatched match is returned.

Parameters

n - integral number specifying which match to examine

Return value

The position of the first character of the specified match or sub-match.

Example

// Run this code

  #include <iostream>
  #include <regex>
  #include <string>

  int main()
  {
      std::regex re("a(a)*b");
      std::string target("aaab");
      std::smatch sm;

      std::regex_match(target, sm, re);
      std::cout << sm.position(1) << '\n';
  }

Output:

  1