# operator+, operator-(std::time_point)

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< cpp‎ | chrono‎ | time point

| (1) |
template< class C, class D1, class R2, class P2 > time_point<C, typename std::common_type<D1, duration<R2,P2>>::type> operator+( const time_point<C,D1>& pt, const duration<R2,P2>& d ); |  | (since C++11) (until C++14)
template< class C, class D1, class R2, class P2 > constexpr time_point<C, typename std::common_type<D1, duration<R2,P2>>::type> operator+( const time_point<C,D1>& pt, const duration<R2,P2>& d ); |  | (since C++14)
| (2) |
template< class R1, class P1, class C, class D2 > time_point<C, typename std::common_type<duration<R1,P1>,D2>::type> operator+( const duration<R1,P1>& d, const time_point<C,D2>& pt ); |  | (since C++11) (until C++14)
template< class R1, class P1, class C, class D2 > constexpr time_point<C, typename std::common_type<duration<R1,P1>,D2>::type> operator+( const duration<R1,P1>& d, const time_point<C,D2>& pt ); |  | (since C++14)
| (3) |
template< class C, class D1, class R2, class P2 > time_point<C, typename std::common_type<D1, duration<R2,P2>>::type> operator-( const time_point<C,D1>& d, const duration<R2,P2>& pt ); |  | (since C++11) (until C++14)
template< class C, class D1, class R2, class P2 > constexpr time_point<C, typename std::common_type<D1, duration<R2,P2>>::type> operator-( const time_point<C,D1>& d, const duration<R2,P2>& pt ); |  | (since C++14)
| (4) |
template< class C, class D1, class D2 > typename std::common_type<D1,D2>::type operator-( const time_point<C,D1>& pt_lhs, const time_point<C,D2>& pt_rhs ); |  | (since C++11) (until C++14)
template< class C, class D1, class D2 > constexpr typename std::common_type<D1,D2>::type operator-( const time_point<C,D1>& pt_lhs, const time_point<C,D2>& pt_rhs ); |  | (since C++14)

Performs add and subtract operations involving a `time_point`.

1-2) Applies the offset `d` to `pt`. Effectively returns CT(pt.time_since_epoch() + d), where `CT` is the return type.
3) Applies the offset `d` to `pt` in negative direction. Effectively returns CT(ot.time_since_epoch() - d), where `CT` is the return type.
4) Computes the difference between `pt_lhs` and `pt_rhs`.

### Parameters

pt | - | a time point to apply the offset to
d | - | a time offset
pt_lhs, pt_rhs | - | time points to extract difference from

### Return value

1-3) The time point that resulted from applying the offset `d`.
4) The duration between the time points.

### Exceptions

(none)

### 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 2739 | C++11 | pt - d behaved erratically for unsigned `duration`s | behavior corrected

### See also

operator+=operator-= | modifies the time point by the given duration (public member function)

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