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Difference between revisions of "cpp/utility/functional/less equal"

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< cpp‎ | utility‎ | functional
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{{cpp/title|less_equal}}
 
{{cpp/title|less_equal}}
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{{cpp/utility/functional/sidebar}}
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{{dcl begin}}
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{{ddcl list header | functional }}
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{{dcl header|functional}}
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{{ddcl list item |
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{{dcl rev multi
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|dcl1=
 
template< class T >
 
template< class T >
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struct less_equal;
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|since2=c++14|dcl2=
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template< class T = void >
 
struct less_equal;
 
struct less_equal;
 
}}
 
}}
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{{ddcl list end}}
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{{dcl end}}
  
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Function object for performing comparisons. Implements {{cpp|operator<{{=}}}} on type {{tt|T}}.
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Function object for performing comparisons. The main template invokes {{c|1=operator<=}} on type {{tt|T}}.
  
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===Member types===
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===Specializations===
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{{tdcl list begin}}
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{{dsc begin}}
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{{tdcl list hitem | type | definition }}
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{{dsc inc|cpp/utility/functional/dsc less_equal_void}}
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{{tdcl list item | {{tt|result_type}} | {{tt|bool}}}}
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{{dsc end}}
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{{tdcl list item | {{tt|first_argument_type}} | {{tt|T}} }}
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{{cpp/utility/functional/member types|result=bool|arg1=T|arg2=T}}
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===Member functions===
 
===Member functions===
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{{dcl list begin}}
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{{dsc begin}}
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{{dcl list mem fun | operator() | nolink=true | checks if the first argument is ''less'' than or ''equal'' to the second}}
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{{dsc mem fun|operator()|nolink=true|checks if the first argument is ''less'' than or ''equal'' to the second}}
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{{dsc end}}
  
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{{member frame | {{small|std::less_equal::}}operator() | 2=
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{{member|{{small|std::less_equal::}}operator()|2=
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{{dcla|constexpr=c++14|1=
 
bool operator()( const T& lhs, const T& rhs ) const;
 
bool operator()( const T& lhs, const T& rhs ) const;
 
}}
 
}}
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{{dcl end}}
  
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Checks if {{tt|lhs}} is ''less'' than or ''equal'' to {{tt|rhs}}.
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Checks if {{c|lhs}} is ''less'' than or ''equal'' to {{c|rhs}}.
  
 
===Parameters===
 
===Parameters===
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{{param list begin}}
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{{par begin}}
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{{param list item | lhs, rhs | values to compare}}
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{{par|lhs, rhs|values to compare}}
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{{par end}}
  
 
===Return value===
 
===Return value===
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{{cpp|true}} if {{cpp|1=lhs <= rhs}}, {{cpp|false}} otherwise.
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{{c|1=lhs <= rhs}}.
  
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===Exceptions===
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If {{tt|T}} is a pointer type, the result is consistent with the [[cpp/language/operator comparison#Pointer total order|implementation-defined strict total order over pointers]].
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(none)
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===Equivalent function===
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{{cpp/impldef exception}}
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{{eq fun cpp | 1=
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bool operator()(const T &lhs, const T &rhs) const  
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===Possible implementation===
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{{eq fun|1=
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constexpr bool operator()(const T& lhs, const T& rhs) const  
 
{
 
{
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     return lhs <= rhs;
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     return lhs <= rhs; // assumes that the implementation handles pointer total order
 
}
 
}
 
}}
 
}}
 
}}
 
}}
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===Defect reports===
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{{dr list begin}}
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{{dr list item|wg=lwg|dr=2562|std=C++98|before=the pointer total order might be inconsistent|after=guaranteed to be consistent}}
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{{dr list end}}
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===See also===
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{{dsc begin}}
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{{dsc inc|cpp/utility/functional/dsc less}}
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{{dsc inc|cpp/utility/functional/ranges/dsc {{SUBPAGENAMEE}}}}
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{{dsc end}}
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{{langlinks|de|es|fr|it|ja|pt|ru|zh}}

Latest revision as of 21:15, 13 July 2024

 
C++
 
Utilities library
General utilities
Relational operators (deprecated in C++20)
 
Function objects
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(C++17)(C++23)
Identity function object
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Transparent operator wrappers
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(C++14)
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(C++14)
(C++14)
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Old binders and adaptors
(until C++17*)
(until C++17*)
(until C++17*)
(until C++17*)
(until C++17*)  
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(until C++17*)(until C++17*)(until C++17*)(until C++17*)
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(until C++17*)(until C++17*)
(until C++17*)(until C++17*)

(until C++17*)
(until C++17*)(until C++17*)(until C++17*)(until C++17*)
(until C++20*)
(until C++20*)
 
Defined in header <functional>
template< class T >
struct less_equal;
 (until C++14)
template< class T = void >
struct less_equal;
 (since C++14)

Function object for performing comparisons. The main template invokes operator<= on type T.

Contents

[edit] Specializations

(C++14)
 function object implementing x <= y deducing parameter and return types
(class template specialization) [edit]

[edit] Member types

Type Definition
result_type (deprecated in C++17)(removed in C++20) bool
first_argument_type (deprecated in C++17)(removed in C++20) T
second_argument_type (deprecated in C++17)(removed in C++20) T

These member types are obtained via publicly inheriting std::binary_function<T, T, bool>.

(until C++11)

[edit] Member functions

operator()
 checks if the first argument is less than or equal to the second
(public member function)

std::less_equal::operator()

bool operator()( const T& lhs, const T& rhs ) const;
 (constexpr since C++14)

Checks if lhs is less than or equal to rhs.

Parameters

lhs, rhs - values to compare

Return value

lhs <= rhs.

If T is a pointer type, the result is consistent with the implementation-defined strict total order over pointers.

[edit] Exceptions

May throw implementation-defined exceptions.

Possible implementation

constexpr bool operator()(const T& lhs, const T& rhs) const 
{
    return lhs <= rhs; // assumes that the implementation handles pointer total order
}

[edit] 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 2562 C++98 the pointer total order might be inconsistent guaranteed to be consistent

[edit] See also

 function object implementing x < y
(class template) [edit]
(C++20)
 constrained function object implementing x <= y
(class) [edit]
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