_reference_t  ](http://en.cppreference.com/w/cpp/types/remove_reference) < T  > & if the argument is an lvalue (i.e. ` T ` is an lvalue reference type), 
  * const  T  otherwise. 

A call to ` ranges::crbegin ` is [ expression-equivalent ](/w/cpp/language/expressions#Expression-equivalence "cpp/language/expressions") to  [ ranges::  rbegin  ](http://en.cppreference.com/w/cpp/ranges/rbegin) (  static_cast  < CT  && > (  t  )  )  .  |  (until C++23)   
---|---  
If the argument is an lvalue or  [ ranges::  enable_borrowed_range
](http://en.cppreference.com/w/cpp/ranges/borrowed_range) < [ std::
remove_cv_t  ](http://en.cppreference.com/w/cpp/types/remove_cv) < T  >> is
true  , then a call to ` ranges::crbegin ` is [ expression-equivalent
](/w/cpp/language/expressions#Expression-equivalence
"cpp/language/expressions") to:

  * [ std::  const_iterator  ](http://en.cppreference.com/w/cpp/iterator/const_iterator) < decltype  (  U  )  > (  U  )  for some expression ` U ` equivalent to  [ ranges::  rbegin  ](http://en.cppreference.com/w/cpp/ranges/rbegin) (  /*possibly-const-range*/  (  t  )  )  . 

In all other cases, a call to ` ranges::crbegin ` is ill-formed, which can result in [ substitution failure ](/w/cpp/language/sfinae "cpp/language/sfinae") when the call appears in the immediate context of a template instantiation.  |  (since C++23)   
  
The return type models  [ std::input_or_output_iterator
](/w/cpp/iterator/input_or_output_iterator "cpp/iterator/input or output
iterator") and [ ` _constant-iterator_ ` ](/w/cpp/ranges/constant_range
"cpp/ranges/constant range") (since C++23)  in all cases.

###  Customization point objects

The name ` ranges::crbegin ` denotes a _customization point object_ , which is
a const [ function object ](/w/cpp/named_req/FunctionObject "cpp/named
req/FunctionObject") of a [ literal ](/w/cpp/named_req/LiteralType "cpp/named
req/LiteralType") [ ` semiregular ` ](/w/cpp/concepts/semiregular
"cpp/concepts/semiregular") class type. For exposition purposes, the cv-
unqualified version of its type is denoted as ` ___crbegin_fn_ ` .

All instances of ` ___crbegin_fn_ ` are equal. The effects of invoking
different instances of type ` ___crbegin_fn_ ` on the same arguments are
equivalent, regardless of whether the expression denoting the instance is an
lvalue or rvalue, and is const-qualified or not (however, a volatile-qualified
instance is not required to be invocable). Thus, ` ranges::crbegin ` can be
copied freely and its copies can be used interchangeably.

Given a set of types ` Args... ` , if  [ std::  declval
](http://en.cppreference.com/w/cpp/utility/declval) < Args  > (  )  ...  meet
the requirements for arguments to ` ranges::crbegin ` above, ` ___crbegin_fn_
` models  

  * [ std::  invocable  ](http://en.cppreference.com/w/cpp/concepts/invocable) < __crbegin_fn, Args...  > , 
  * [ std::  invocable  ](http://en.cppreference.com/w/cpp/concepts/invocable) < const  __crbegin_fn, Args...  > , 
  * [ std::  invocable  ](http://en.cppreference.com/w/cpp/concepts/invocable) < __crbegin_fn  & , Args...  > , and 
  * [ std::  invocable  ](http://en.cppreference.com/w/cpp/concepts/invocable) < const  __crbegin_fn  & , Args...  > .   

Otherwise, no function call operator of ` ___crbegin_fn_ ` participates in
overload resolution.

###  [ [ edit
](/mwiki/index.php?title=cpp/ranges/crbegin&action=edit&section=1 "Edit
section: Example") ]  Example

Run this code

    
    
    #include <cassert>
    #include <iterator>
    #include <span>
    #include <vector>
     
    int main()
    {
        [std::vector](http://en.cppreference.com/w/cpp/container/vector)<int> v{3, 1, 4};
        auto vi = std::[ranges::crbegin](http://en.cppreference.com/w/cpp/ranges-ranges-placeholder/crbegin)(v);
        [assert](http://en.cppreference.com/w/cpp/error/assert)(*vi == 4);
        ++vi; // OK, iterator object is mutable
        [assert](http://en.cppreference.com/w/cpp/error/assert)(*vi == 1);
        // *vi = 13; // Er