Namespace
Varianti

std::prev

Da cppreference.com.
< cpp‎ | iterator

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C++
 
Biblioteca Iterator
Primitive iteratori
Original:
Iterator primitives
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iterator_traits
input_iterator_tag
output_iterator_tag
forward_iterator_tag
bidirectional_iterator_tag
random_access_iterator_tag
iterator
Adattatori iteratori
Original:
Iterator adaptors
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reverse_iterator
Flusso iteratori
Original:
Stream iterators
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istream_iterator
ostream_iterator
istreambuf_iterator
ostreambuf_iterator
Operazioni di iteratori
Original:
Iterator operations
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advance
distance
prev(C++11)
next(C++11)
Intervallo accesso
Original:
Range access
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begin(C++11)
end(C++11)
 
Elemento definito nell'header <iterator>
template< class BidirIt >

BidirIt prev( BidirIt it,

              typename std::iterator_traits<BidirIt>::difference_type n = 1 );
 (dal C++11)
Restituisce il predecessore nth di it iteratore.
Original:
Return the nth predecessor of iterator it.
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Indice

[modifica] Parametri

it -
un iteratore
Original:
an iterator
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n -
numero di it elementi dovrebbero essere disceso
Original:
number of elements it should be descended
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Type requirements
-
BidirIt must meet the requirements of BidirectionalIterator.

[modifica] Valore di ritorno

Il predecessore di nth it iteratore.
Original:
The nth predecessor of iterator it.
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[modifica] Possibile implementazione

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

[modifica] Esempio

#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

[modifica] Vedi anche

(C++11)
incrementare un iteratore
Original:
increment an iterator
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(funzione) [modifica]
avanza di un iteratore per distanza data
Original:
advances an iterator by given distance
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(funzione) [modifica]
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