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std::find, std::find_if, std::find_if_not

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Algorithm Bibliothek
Funktionen
Original:
Functions
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Nicht-modifizierende Sequenz Operationen
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Non-modifying sequence operations
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find
find_if
find_if_not


(C++11)
find_end
find_first_of
adjacent_find
search
search_n
Modifizierende Sequenz Operationen
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Modifying sequence operations
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Partitionierungsoperationen
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Partitioning operations
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Sortierung Operationen (auf sortierten Bereiche)
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Sorting operations (on sorted ranges)
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Binary Suchaktionen (auf sortierten Bereiche)
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Binary search operations (on sorted ranges)
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Set-Operationen (auf sortierten Bereiche)
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Set operations (on sorted ranges)
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Heap-Operationen
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Heap operations
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Minimum / Maximum Operationen
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Minimum/maximum operations
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Numerische Operationen
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Numeric operations
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C-Bibliothek
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C library
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Defined in header <algorithm>
template< class InputIt, class T >
InputIt find( InputIt first, InputIt last, const T& value );
(1)
template< class InputIt, class UnaryPredicate >

InputIt find_if( InputIt first, InputIt last,

                 UnaryPredicate p );
(2)
template< class InputIt, class UnaryPredicate >

InputIt find_if_not( InputIt first, InputIt last,

                     UnaryPredicate q );
(3) (seit C++11)
Diese Funktionen finden Sie das erste Element im Bereich [first, last), die bestimmte Kriterien erfüllt:
Original:
These functions find the first element in the range [first, last) that satisfies specific criteria:
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Ein. find Suche nach einem Element gleich value
Original:
1. find searches for an element equal to value
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2. find_if sucht nach einem Element, für das Prädikat p kehrt true
Original:
2. find_if searches for an element for which predicate p returns true
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3. find_if_not sucht Element, für das Prädikat q kehrt false
Original:
3. find_if_not searches for element for which predicate q returns false
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Inhaltsverzeichnis

[Bearbeiten] Parameter

first, last -
das Spektrum der Elemente zu untersuchen
Original:
the range of elements to examine
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value -
Wert auf die Elemente zu vergleichen
Original:
value to compare the elements to
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p - unary predicate which returns ​true
für das gewünschte Element
Original:
for the required element
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.

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

 bool pred(const Type &a);

The signature does not need to have const &, but the function must not modify the objects passed to it.
The type Type must be such that an object of type InputIt can be dereferenced and then implicitly converted to Type. ​

q - unary predicate which returns ​false
für das gewünschte Element
Original:
for the required element
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.

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

 bool pred(const Type &a);

The signature does not need to have const &, but the function must not modify the objects passed to it.
The type Type must be such that an object of type InputIt can be dereferenced and then implicitly converted to Type. ​

Type requirements
-
InputIt must meet the requirements of InputIterator.

[Bearbeiten] Rückgabewert

Iterator auf das erste Element, die der Bedingung oder last wenn ein solches Element gefunden wird .
Original:
Iterator to the first element satisfying the condition or last if no such element is found.
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[Bearbeiten] Komplexität

An den meisten last - first Anwendungen des Prädikats
Original:
At most last - first applications of the predicate
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[Bearbeiten] Mögliche Implementierung

First version
template<class InputIt, class T>
InputIt find(InputIt first, InputIt last, const T& value)
{
    for (; first != last; ++first) {
        if (*first == value) {
            return first;
        }
    }
    return last;
}
Second version
template<class InputIt, class UnaryPredicate>
InputIt find_if(InputIt first, InputIt last, UnaryPredicate p)
{
    for (; first != last; ++first) {
        if (p(*first)) {
            return first;
        }
    }
    return last;
}
Third version
template<class InputIt, class UnaryPredicate>
InputIt find_if_not(InputIt first, InputIt last, UnaryPredicate q)
{
    for (; first != last; ++first) {
        if (!q(*first)) {
            return first;
        }
    }
    return last;
}
Wenn Sie keinen C + +11, ein Äquivalent zu std::find_if_not ist std::find_if mit dem negierten Prädikat verwenden .
Original:
If you do not have C++11, an equivalent to std::find_if_not is to use std::find_if with the negated predicate.
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template<class InputIt, class UnaryPredicate>
InputIt find_if_not(InputIt first, InputIt last, UnaryPredicate q)
{
    return std::find_if(first, last, std::not1(q));
}

[Bearbeiten] Beispiel

Im folgenden Beispiel wird eine ganze Zahl in einem Vektor von ganzen Zahlen .
Original:
The following example finds an integer in a vector of integers.
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#include <iostream>
#include <algorithm>
#include <vector>
 
int main()
{
    int n1 = 3;
    int n2 = 5;
 
    std::vector<int> v{0, 1, 2, 3, 4};
 
    auto result1 = std::find(v.begin(), v.end(), n1);
    auto result2 = std::find(v.begin(), v.end(), n2);
 
    if (result1 != v.end()) {
        std::cout << "v contains: " << n1 << '\n';
    } else {
        std::cout << "v does not contain: " << n1 << '\n';
    }
 
    if (result2 != v.end()) {
        std::cout << "v contains: " << n2 << '\n';
    } else {
        std::cout << "v does not contain: " << n2 << '\n';
    }
}

Output:

v contains: 3
v does not contain: 5

[Bearbeiten] Siehe auch

findet zwei identischen (oder eine andere Beziehung) Elemente einander benachbart
Original:
finds two identical (or some other relationship) items adjacent to each other
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(Funktions-Template) [edit]
findet die letzte Sequenz von Elementen in einem bestimmten Bereich
Original:
finds the last sequence of elements in a certain range
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(Funktions-Template) [edit]
searches for any one of a set of elements
(Funktions-Template) [edit]
findet die erste Position, wo zwei Bereiche unterscheiden
Original:
finds the first position where two ranges differ
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(Funktions-Template) [edit]
searches for a range of elements
(Funktions-Template) [edit]