std::find, std::find_if, std::find_if_not - cppreference.com
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      std::find, std::find_if, std::find_if_not

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      C++
       
      Biblioteca algoritmo
      Funções
      Original:
      Functions
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      Não modificar operações de seqüência
      Original:
      Non-modifying sequence operations
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      Modificando operações de seqüência
      Original:
      Modifying sequence operations
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      Particionamento operações
      Original:
      Partitioning operations
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      Operações de classificação (em intervalos ordenados)
      Original:
      Sorting operations (on sorted ranges)
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      Binários operações de busca (em intervalos ordenados)
      Original:
      Binary search operations (on sorted ranges)
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      Definir operações (em intervalos ordenados)
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      Set operations (on sorted ranges)
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      Operações de pilha
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      Heap operations
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      Mínimo / máximo de operações
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      Minimum/maximum operations
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      Operações numéricas
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      Numeric operations
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      C biblioteca
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      C library
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      <tbody> </tbody>
      Definido no cabeçalho <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) (desde C++11)
      Estas funções encontraam o primeiro elemento no intervalo [first, last) que satisfaz critérios específicos:
      Original:
      These functions find the first element in the range [first, last) that satisfies specific criteria:
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      1. find procura por um elemento igual a value
      Original:
      1. find searches for an element equal to value
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      2. find_if procura um elemento para o qual predicado p retornos true
      Original:
      2. find_if searches for an element for which predicate p returns true
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      3. find_if_not pesquisas de elemento para o qual predicado q retornos false
      Original:
      3. find_if_not searches for element for which predicate q returns false
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      Parâmetros

      first, last -
      a gama de elementos para examinar
      Original:
      the range of elements to examine
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      value -
      valor a comparar os elementos de
      Original:
      value to compare the elements to
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      p - unary predicate which returns ​true
      para o elemento desejado
      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
      para o elemento desejado
      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.

      Valor de retorno

      Iterador para o primeiro elemento que satisfaça a condição ou last se nenhum elemento for encontrado.
      Original:
      Iterator to the first element satisfying the condition or last if no such element is found.
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      Complexidade

      No máximo last - first aplicações do predicado
      Original:
      At most last - first applications of the predicate
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      Possível implementação

      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;
}
      Se você não tem C + 11, equivalente a std::find_if_not é usar std::find_if com o predicado negado.
      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));
}

      Exemplo

      O exemplo a seguir localiza um número inteiro em um vetor de inteiros .
      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';
    }
}

      Saída: 

      v contains: 3
v does not contain: 5

      Veja também