NAME

std::match_results::prefix - std::match_results::prefix

Synopsis

const_reference prefix() const; (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.

The behavior is undefined unless ready() == true

Parameters

(none)

Return value

Reference to the unmatched prefix.

Example

// Run this code

#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';
}

Output:

b

See also

returns sub-sequence between the end of the full match and the end of the
suffix target sequence
(public member function)