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std::generate_n – cppreference.com

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definiert in Header

<algorithm>

template< class OutputIt, class Size, class Generator > void generate_n( OutputIt first, Size count, Generator g ); template< class OutputIt, class Size, class Generator > OutputIt generate_n( OutputIt first, Size count, Generator g );

(bis C + +11)

(seit C++11)

Werte zuweist, erzeugt durch gegebene Funktion Objekt g, um den ersten count Elemente im Bereich beginnend bei first, wenn count>0. Tut nichts anderes .

Original:

Assigns values, generated by given function object g, to the first count elements in the range beginning at first, if count>0. Does nothing otherwise.

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Parameter

first -

der Beginn des Bereichs von Elementen zu erzeugen

Original:

the beginning of the range of elements to generate

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count -

Einige der Elemente zu erzeugen

Original:

number of the elements to generate

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g - generator function object that will be called.

The signature of the function should be equivalent to the following:

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The type Ret must be such that an object of type OutputIt can be dereferenced and assigned a value of type Ret. ​

Type requirements
-OutputIt must meet the requirements of OutputIterator.

Rückgabewert

(None) (bis C + +11)

Original:

(none) (bis C + +11)

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Iterator ein nach dem letzten Element, wenn count>0, first anderweitig zugeordnet. (seit C++11)

Original:

Iterator one past the last element assigned if count>0, first otherwise. (seit C++11)

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Komplexität

Genau count Anrufungen g() und Zuweisungen für count>0 .

Original:

Exactly count invocations of g() and assignments, for count>0.

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Mögliche Implementierung

template< class OutputIt, class Size, class Generator >
OutputIt generate_n( OutputIt first, Size count, Generator g )
{
    for( Size i = 0; i < count; i++ ) {
        *first++ = g();
    }
    return first;
}

Beispiel

Der folgende Code füllt ein Array von Ganzzahlen mit Zufallszahlen .

Original:

The following code fills an array of integers with random numbers.

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#include <cstddef>
#include <cstdlib>
#include <iostream>
#include <iterator>
#include <algorithm>
 
int main()
{
    const std::size_t N = 5;
    int ar[N];
    std::generate_n(ar, N, std::rand); // Using the C function rand()
 
    std::cout << "ar: ";
    std::copy(ar, ar+N, std::ostream_iterator<int>(std::cout, " "));
    std::cout << "\n";
}

Output:

52894 15984720 41513563 41346135 51451456

Siehe auch

weist einen Wert auf eine Reihe von Elementen

Original:

assigns a value to a number of elements

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(Funktions-Template) [edit]

speichert das Ergebnis einer Funktion in einem Bereich

Original:

saves the result of a function in a range

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(Funktions-Template) [edit]