std::sub_match<BidirIt>::swap

 

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std::sub_match

Member functions

sub_match::sub_match

sub_match::length

sub_match::strsub_match::operator string_type

sub_match::compare

sub_match::swap

Non-member functions

operator==operator!=operator<<operator<=operator>operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)

operator<<

 

void swap( sub_match& s ) noexcept(/* see below */);		(since C++11)

Exchanges the contents of two sub-match objects. Equivalent to

this->pair<BidirIt, BidirIt>::swap(s);
std::swap(matched, s.matched);

Parameters

s	-	a sub_match to swap with
Type requirements
- BidirIt must meet the requirements of LegacySwappable.

Exceptions

noexcept specification:  

noexcept(std::is_nothrow_swappable_v<BidirIt>)

Example

Run this code

#include <cassert>
#include <iostream>
#include <regex>
 
int main()
{
    const char* s = "Quick red cat";
    std::sub_match<const char*> x, y;
 
    x.first = &s[0];
    x.second = &s[5];
    x.matched = false;
 
    y.first = &s[012];
    y.second = &s[13];
    y.matched = true;
 
    std::cout << "Before swap:\n";
    std::cout << "x.str() = [" << x.str() << "]\n";
    std::cout << "y.str() = [" << y.str() << "]\n";
    assert(!x.matched and y.matched);
 
    x.swap(y);
 
    std::cout << "After swap:\n";
    std::cout << "x.str() = [" << x.str() << "]\n";
    std::cout << "y.str() = [" << y.str() << "]\n";
    assert(x.matched and !y.matched);
}

Output:

Before swap:
x.str() = []
y.str() = [cat]
After swap:
x.str() = [cat]
y.str() = []

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 3204	C++11	std::sub_match used inherited std::pair::swap(pair&) which led to a slicing	std::sub_match::swap(sub_match&) is added