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Difference between revisions of "cpp/string/basic string/swap2"

From cppreference.com
< cpp‎ | string‎ | basic string
(note LWG2064)
m (Add example (copy from basic_string/dsc swap))
Line 36: Line 36:
 
===Exceptions===
 
===Exceptions===
 
{{noexcept|noexcept(lhs.swap(rhs))}}
 
{{noexcept|noexcept(lhs.swap(rhs))}}
 +
}}
 +
 +
===Example===
 +
{{example
 +
| code=
 +
#include <string>
 +
#include <iostream>
 +
 +
int main()
 +
{
 +
    std::string a = "AAA";
 +
    std::string b = "BBB";
 +
 +
    std::cout << "before swap" << '\n';
 +
    std::cout << "a: " << a << '\n';
 +
    std::cout << "b: " << b << '\n';
 +
 +
    std::swap(a,b);
 +
 +
    std::cout << "after swap" << '\n';
 +
    std::cout << "a: " << a << '\n';
 +
    std::cout << "b: " << b << '\n';
 +
}
 +
 +
| output=
 +
before swap
 +
a: AAA
 +
b: BBB
 +
after swap
 +
a: BBB
 +
b: AAA
 
}}
 
}}
  

Revision as of 15:17, 18 January 2022

 
C++
 
Strings library
 
std::basic_string
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Non-member functions
swap(std::basic_string)
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Defined in header <string>
template< class CharT, class Traits, class Alloc >

void swap( std::basic_string<CharT, Traits, Alloc> &lhs,

           std::basic_string<CharT, Traits, Alloc> &rhs );
 (until C++17)
template< class CharT, class Traits, class Alloc >

void swap( std::basic_string<CharT, Traits, Alloc> &lhs,

           std::basic_string<CharT, Traits, Alloc> &rhs ) noexcept(/* see below */);
 (since C++17)
(until C++20)
template< class CharT, class Traits, class Alloc >

constexpr void
    swap( std::basic_string<CharT, Traits, Alloc> &lhs,

          std::basic_string<CharT, Traits, Alloc> &rhs ) noexcept(/* see below */);
 (since C++20)

Specializes the std::swap algorithm for std::basic_string. Swaps the contents of lhs and rhs. Equivalent to lhs.swap(rhs).

Contents

Parameters

lhs, rhs - strings whose contents to swap

Return value

(none)

Complexity

Constant.

Exceptions

noexcept specification:  
noexcept(noexcept(lhs.swap(rhs)))
 (since C++17)

Example

Run this code
#include <string>
#include <iostream>
 
int main() 
{
    std::string a = "AAA";
    std::string b = "BBB";
 
    std::cout << "before swap" << '\n';
    std::cout << "a: " << a << '\n';
    std::cout << "b: " << b << '\n';
 
    std::swap(a,b);
 
    std::cout << "after swap" << '\n';
    std::cout << "a: " << a << '\n';
    std::cout << "b: " << b << '\n';
}

Output: 

before swap
a: AAA
b: BBB
after swap
a: BBB
b: AAA

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 2064 C++11 non-member swap was noexcept and inconsistent with member swap noexcept removed

See also

 swaps the contents
(public member function) [edit]
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