std::unique_copy

 

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Definido en la cabecera <algorithm>
template< class InputIt, class OutputIt > ForwardIt unique_copy( InputIt first, InputIt last,                        OutputIt d_first );	(1)
template< class InputIt, class OutputIt, class BinaryPredicate > ForwardIt unique_copy( InputIt first, InputIt last,                        OutputIt d_first, BinaryPredicate p );	(2)

Copia los elementos de la [first, last) rango, a otro principio rango en d_first de tal manera que no hay elementos iguales consecutivos. Sólo el primer elemento de cada grupo de elementos iguales se copia. La primera versión utiliza operator== para comparar los elementos, la segunda versión utiliza el predicado binario dado p .

Original:

Copies the elements from the range [first, last), to another range beginning at d_first in such a way that there are no consecutive equal elements. Only the first element of each group of equal elements is copied. The first version uses operator== to compare the elements, the second version uses the given binary predicate p.

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Parámetros

first, last	-	el intervalo de elementos de proceso Original: the range of elements to process The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
d_first	-	el comienzo del rango de destino Original: the beginning of the destination range The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
p	-	binary predicate which returns ​true if the elements should be treated as equal. The signature of the predicate function should be equivalent to the following:  bool pred(const Type1 &a, const Type2 &b); The signature does not need to have const &, but the function must not modify the objects passed to it. The types Type1 and Type2 must be such that an object of type ForwardIt can be dereferenced and then implicitly converted to both of them. ​
Requerimientos de tipo
- InputIt debe reunir los requerimientos de InputIterator.
- OutputIt debe reunir los requerimientos de OutputIterator.
- The type of dereferenced InputIt must meet the requirements of CopyAssignable.
- The type of dereferenced InputIt must meet the requirements of CopyConstructible. if neither InputIt nor OutputIt satisfies ForwardIterator

Valor de retorno

Salida de iterador al elemento más allá del último elemento escrito

Original:

Output iterator to the element past the last written element

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Posible implementación

Primera versión
template<class ForwardIt, class OutputIt> ForwardIt unique_copy(ForwardIt first, ForwardIt last, OutputIt d_first) {   if (first == last) return d_first;   *d_first = *first; while (++first != last) { if (!(*d_first == *first)) { *(++d_first) = *first; } } return ++d_first; }
Segunda versión
template<class ForwardIt, class OutputIt, class BinaryPredicate> ForwardIt unique_copy(ForwardIt first, ForwardIt last, OutputIt d_first, BinaryPredicate p) {   if (first == last) return d_first;   *d_first = *first; while (++first != last) { if (!p(*result, *first)) { *(++d_first) = *first; } } return ++d_first; }

Ejemplo

Los adornos de los siguientes programas todos los múltiples espacios consecutivos en una cadena constante e imprime el resultado

Original:

The following program trims all multiple consecutive spaces in a const string and prints the result

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#include <string>
#include <iostream>
#include <algorithm>
#include <iterator>
 
int main()
{
    std::string s1 = "The      string    with many       spaces!";
    std::cout << "before: " << s1 << '\n';
 
    std::string s2;
    std::unique_copy(s1.begin(), s1.end(), std::back_inserter(s2),
                     [](char c1, char c2){ return c1 == ' ' && c2 == ' '; });
 
    std::cout << "after:  " << s2 << '\n';
}

Salida:

before: The      string    with many       spaces!
after:  The string with many spaces!

Complejidad

lineal en la distancia entre first y last

Original:

linear in the distance between first and last

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Ver también

adjacent_find	encuentra dos elementos contiguos idénticos (o que satisfacen un predicado) (plantilla de función)
unique	removes consecutive duplicate elements in a range (plantilla de función)