xtd::iequatable< type_t > Class Template Reference

Inheritance diagram for xtd::iequatable< type_t >:

Definition

template<typename type_t>
class xtd::iequatable< type_t >

Defines a generalized method that a value type or class implements to create a type-specific method for determining equality of instances.

Namespace

xtd

Library

xtd.core

Remarks

This interface is implemented by types whose values can be equated (for example, the numeric and string classes). A value type or class implements the equals method to create a type-specific method suitable for determining equality of instances.

The xtd::icomparable<type_t> interface defines the compare_to method, which determines the sort order of instances of the implementing type. The iequatable<T> interface defines the equals method, which determines the equality of instances of the implementing type.

Examples

The following example shows how to use xtd::iequatable interface.

#include <xtd/xtd>
 
class foo : public iequatable<foo> {
public:
  explicit foo(int value) : value_ {value} {}
 
  auto equals(const foo& value) const noexcept -> bool override {return value_ == value.value_;}
  
private:
  int value_ = 0;
};
 
auto main() -> int {
  console::write_line("foo {{42}}.equals(foo {{42}}) = {}", foo {42}.equals(foo {42}));
  console::write_line("foo {{42}}.equals(foo {{84}}) = {}", foo {42}.equals(foo {84}));
  console::write_line();
  
  console::write_line("!foo {{42}}.equals(foo {{42}}) = {}", !foo {42}.equals(foo {42}));
  console::write_line("!foo {{42}}.equals(foo {{84}}) = {}", !foo {42}.equals(foo {84}));
  console::write_line();
  
  console::write_line("foo {{42}} == foo {{42}} = {}", foo {42} == foo {42});
  console::write_line("foo {{42}} == foo {{84}} = {}", foo {42} == foo {84});
  console::write_line();
  
  console::write_line("foo {{42}} != foo {{42}} = {}", foo {42} != foo {42});
  console::write_line("foo {{42}} != foo {{84}} = {}", foo {42} != foo {84});
}
 
// This code produces the following output :
//
// foo {42}.equals(foo {42}) = true
// foo {42}.equals(foo {84}) = false
 
// !foo {42}.equals(foo {42}) = false
// !foo {42}.equals(foo {84}) = true
 
// foo {42} == foo {42} = true
// foo {42} == foo {84} = false
 
// foo {42} != foo {42} = false
// foo {42} != foo {84} = true

Remarks

Implementing xtd::iequatable<T> automatically enables the equality operators (operator == and operator !=) based on the equals(const type_t& obj) method.

Public Methods
virtual auto	equals (const type_t &) const noexcept -> bool=0
	Indicates whether the current object is equal to another object of the same type.

Member Function Documentation

equals()

template<typename type_t>

virtual auto xtd::iequatable< type_t >::equals ( const type_t & ) const -> bool

nodiscardpure virtualnoexcept

Indicates whether the current object is equal to another object of the same type.

Parameters

obj	An object to compare with this object.

Returns

true if the current object is equal to the other parameter; otherwise, false.

Implemented in xtd::any_object, xtd::basic_string< char_t, traits_t, allocator_t >, xtd::console_key_info, xtd::date_time, xtd::diagnostics::switch_object, xtd::diagnostics::trace_listener_collection, xtd::forms::message_notifier_button, xtd::globalization::culture_info, xtd::guid, xtd::index, xtd::net::dns_end_point, xtd::net::ip_address, xtd::net::ip_end_point, xtd::net::socket_address, xtd::net::sockets::ip_packet_information, xtd::net::sockets::ip_v6_multicast_option, xtd::net::sockets::linger_option, xtd::net::sockets::multicast_option, xtd::range, xtd::reflection::assembly, xtd::reflection::assembly_company_attribute, xtd::reflection::assembly_configuration_attribute, xtd::reflection::assembly_copyright_attribute, xtd::reflection::assembly_culture_attribute, xtd::reflection::assembly_description_attribute, xtd::reflection::assembly_file_version_attribute, xtd::reflection::assembly_guid_attribute, xtd::reflection::assembly_identifier_attribute, xtd::reflection::assembly_name_attribute, xtd::reflection::assembly_product_attribute, xtd::reflection::assembly_title_attribute, xtd::reflection::assembly_trademark_attribute, xtd::reflection::assembly_version_attribute, xtd::time_span, xtd::time_zone_info, xtd::toolkit, xtd::type_object, xtd::uri, and xtd::version.

---

The documentation for this class was generated from the following file:

• xtd.core/include/xtd/iequatable.hpp