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std::prev

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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.

Contents

[edit] Parameters

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

[edit] Return value

The nth predecessor of iterator it.

[edit] Possible implementation

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

[edit] Example

#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

[edit] See also

(C++11)
increment an iterator
(function) [edit]
advances an iterator by given distance
(function) [edit]