std::basic_string<CharT,Traits,Allocator>::swap

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[edit]

Strings library

Classes
basic_string
basic_string_view (C++17)
char_traits

[edit]

std::basic_string

Member functions
basic_string::basic_string
basic_string::~basic_string
basic_string::operator=
basic_string::assign
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basic_string::get_allocator
Element access
basic_string::at
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basic_string::data
basic_string::c_str
basic_string::operator basic_string_view (C++17)
Iterators
basic_string::beginbasic_string::cbegin (C++11)
basic_string::endbasic_string::cend (C++11)
basic_string::rbeginbasic_string::crbegin (C++11)
basic_string::rendbasic_string::crend (C++11)
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Modifiers
basic_string::clear
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basic_string::copy
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basic_string::swap
Capacity
basic_string::empty
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basic_string::shrink_to_fit (DR*)
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basic_string::compare
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basic_string::contains (C++23)
basic_string::substr

swap(std::basic_string)

erase(std::basic_string)erase_if(std::basic_string)

(C++20)(C++20)

operator==operator!=operator<operator>operator<=operator>=operator<=>

(until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)

Numeric conversions

stoistolstoll (C++11)(C++11)(C++11)
stoulstoull (C++11)(C++11)

stofstodstold (C++11)(C++11)(C++11)
to_string (C++11)
to_wstring (C++11)

Literals

operator""s

(C++14)

Helper classes

hash<std::basic_string>

(C++11)

Deduction guides(C++17)

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void swap( basic_string& other);		(until C++17)
void swap( basic_string& other)noexcept(/* see below */);		(since C++17) (constexpr since C++20)

Exchanges the contents of the string with those ofother. All iterators and references may be invalidated.

Ifstd::allocator_traits<allocator_type>::propagate_on_container_swap::value istrue, then the allocators are exchanged using an unqualified call to non-memberswap. Otherwise, they are not swapped (and ifget_allocator()!= other.get_allocator(), the behavior is undefined).

(since C++11)

[edit]Parameters

other

string to exchange the contents with

[edit]Complexity

Constant.

[edit]Exceptions

No exception is thrown.

(until C++11)

No exception is thrown, unless the behavior is undefined.

If an exception is thrown for any reason, this function has no effect (strong exception safety guarantee).

(since C++11)

noexcept specification:

noexcept(std::allocator_traits<Allocator>::propagate_on_container_swap::value||
std::allocator_traits<Allocator>::is_always_equal::value)

(since C++17)

[edit]Example

Run this code

#include <iostream>#include <string> int main(){std::string a="AAA";std::string b="BBBB"; std::cout<<"Before swap:\n""a = "<< a<<"\n""b = "<< b<<"\n\n";     a.swap(b); std::cout<<"After swap:\n""a = "<< a<<"\n""b = "<< b<<'\n';}

Output:

Before swap:a = AAAb = BBBB After swap:a = BBBBb = AAA

[edit]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 403	C++98	`swap()` might throw an exception	no exception is thrown
LWG 535	C++98	swapping strings did not preserve the character orders	orders are also preserved
LWG 2151 (P1148R0)	C++11	no exception was thrown in the case of unequal non-propagating allocators	the behavior is undefined in this case

[edit]See also

swap	swaps the values of two objects (function template)[edit]
swap_ranges	swaps two ranges of elements (function template)[edit]
swap	swaps the contents (public member function of`std::basic_string_view<CharT,Traits>`)[edit]