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

Since C++11

Obtains a reference to the std::sub_match object representing the target sequence between the start of the beginning of the target sequence and the start of the entire match of the regular expression.

# Declarations

const_reference prefix() const;

(since C++11)

# Return value

Reference to the unmatched prefix.

# Example

#include <iostream>
#include <regex>
#include <string>
 
int main()
{
    std::regex re("a(a)*b");
    std::string target("baaaby");
    std::smatch sm;
 
    std::regex_search(target, sm, re);
    std::cout << sm.prefix().str() << '\n';
}

# See also