std::prev

 

C++

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Iterator library

Iterator primitives
iterator_traits
input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tag
iterator
Iterator adaptors
reverse_iterator move_iterator (C++11) back_insert_iterator front_insert_iterator insert_iterator	make_reverse_iterator (C++14) make_move_iterator (C++11) back_inserter front_inserter inserter
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distance
prev (C++11)
next (C++11)
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begincbegin (C++11)(C++14)
endcend (C++11)(C++14)
rbegincrbegin (C++14)(C++14)
rendcrend (C++14)(C++14)

 

Defined in header <iterator>
template< class BidirIt > BidirIt prev( BidirIt it,               typename std::iterator_traits<BidirIt>::difference_type n = 1 );		(since C++11)

Return the nth predecessor of iterator it.

Parameters

it	-	an iterator
n	-	number of elements it should be descended
Type requirements
- BidirIt must meet the requirements of BidirectionalIterator.

Return value

The nth predecessor of iterator it.

Possible implementation

template<class BidirIt> BidirIt prev(BidirIt it, typename std::iterator_traits<BidirIt>::difference_type n = 1) { std::advance(it, -n); return it; }

Example

Run this code

#include <iostream>
#include <iterator>
#include <vector>
 
int main() 
{
    std::vector<int> v{ 3, 1, 4 };
 
    auto it = v.end();
 
    auto pv = std::prev(it, 2);
 
    std::cout << *pv << '\n';
}

Output:

1

See also

next (C++11)	increment an iterator (function)
advance	advances an iterator by given distance (function)