[#mp_units-operator_minus-01]
= xref:mp_units.adoc[mp_units]::operator‐
:relfileprefix: ../
:mrdocs:

Subtraction operator

== Synopsis

Declared in `<mp‐units/framework/quantity_point.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    auto R1,
    auto PO1,
    typename Rep1,
    xref:mp_units/QuantityPointOf.adoc[QuantityPointOf<mp_units::detail::get_absolute_point_origin(PO1)>] QP2>
[[nodiscard]]
constexpr
xref:mp_units/Quantity-0c.adoc[Quantity] auto
operator‐(
    xref:mp_units/quantity_point-08.adoc[quantity_point<R1, PO1, Rep1>] const& lhs,
    QP2 const& rhs)
requires requires { lhs.quantity_ref_from(PO1) ‐ rhs.quantity_ref_from(QP2::point_origin); };
----

[NOTE]
====
This function is a https://en.cppreference.com/w/cpp/language/friend[hidden friend] of xref:mp_units/quantity_point-08.adoc[quantity_point], declared inside an implementation-defined base class: it can be found only through argument-dependent lookup.
====

== Return Value

[NOTE]
====
The return value https://en.cppreference.com/cpp/language/attributes/nodiscard[should not be discarded^].
====
== Parameters

[cols="1,4"]
|===
| Name| Description
| *lhs*
| The left operand
| *rhs*
| The right operand
|===


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