std::chrono::duration<Rep,Period>:: operator+ (unary) , std::chrono::duration<Rep,Period>:: operator- (unary)

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(1)
constexpr duration operator + ( ) const ;
(until C++17)
constexpr std:: common_type_t < duration > operator + ( ) const ;
(since C++17)
(2)
constexpr duration operator - ( ) const ;
(until C++17)
constexpr std:: common_type_t < duration > operator - ( ) const ;
(since C++17)

Implements unary plus and unary minus for the durations.

If rep_ is a member variable holding the number of ticks in a duration object, and D is the return type,

1) Equivalent to return D ( * this ) ; .
2) Equivalent to return D ( - rep_ ) ; .

Parameters

(none)

Return value

1) A copy of this duration object.
2) A copy of this duration object, with the number of ticks negated.

Example

Run this code 
#include <chrono>
#include <iostream>
 
int main()
{
    constexpr std::chrono::seconds s1(-052);
    constexpr std::chrono::seconds s2 = -s1;
 
    std::cout << "Negated " << s1 << " are " << s2 << '\n';
}

Output: 

Negated -42s are 42s

See also

increments or decrements the tick count
(public member function)
(C++11)
implements arithmetic operations with durations as arguments
(function template)
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