std::count, std::count_if

 

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Funções Original: Functions The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
Não modificar operações de seqüência Original: Non-modifying sequence operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
all_ofany_ofnone_of (C++11)(C++11)(C++11) for_each countcount_if mismatch equal	findfind_iffind_if_not (C++11) find_end find_first_of adjacent_find search search_n
Modificando operações de seqüência Original: Modifying sequence operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
copycopy_if (C++11) copy_n (C++11) copy_backward move (C++11) move_backward (C++11) fill fill_n transform generate generate_n removeremove_if remove_copyremove_copy_if	replacereplace_if replace_copyreplace_copy_if swap swap_ranges iter_swap reverse reverse_copy rotate rotate_copy random_shuffleshuffle  (C++11) unique unique_copy
Particionamento operações Original: Partitioning operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
is_partitioned (C++11) partition partition_copy (C++11)	stable_partition partition_point (C++11)
Operações de classificação (em intervalos ordenados) Original: Sorting operations (on sorted ranges) The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
is_sorted (C++11) is_sorted_until (C++11) sort	partial_sort partial_sort_copy stable_sort nth_element
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lower_bound upper_bound	binary_search equal_range
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merge inplace_merge includes	set_difference set_intersection set_symmetric_difference set_union
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is_heap is_heap_until (C++11) make_heap	push_heap pop_heap sort_heap
Mínimo / máximo de operações Original: Minimum/maximum operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
max max_element min min_element minmax (C++11) minmax_element (C++11)	lexicographical_compare is_permutation (C++11) next_permutation prev_permutation
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iota (C++11) accumulate inner_product	adjacent_difference partial_sum
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qsort	bsearch

 

Definido no cabeçalho <algorithm>
template<class InputIt, class T > typename iterator_traits<InputIt>::difference_type     count( InputIt first, InputIt last, const T &value );	(1)
template<class InputIt, class UnaryPredicate > typename iterator_traits<InputIt>::difference_type     count_if( InputIt first, InputIt last, UnaryPredicate p );	(2)

Retorna o número de elementos no intervalo [first, last) satisfazer critérios específicos. A primeira versão conta os elementos que são iguais para value, a segunda versão conta com elementos para os quais predicado p retornos true.

Original:

Returns the number of elements in the range [first, last) satisfying specific criteria. The first version counts the elements that are equal to value, the second version counts elements for which predicate p returns true.

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Parâmetros

first, last	-	a gama de elementos para examinar Original: the range of elements to examine The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
value	-	o valor a ser procurado Original: the value to search for The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
p	-	unary predicate which returns ​true para os elementos necessários Original: for the required elements The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. . 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

número de elementos que satisfaz a condição.

Original:

number of elements satisfying the condition.

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Complexidade

exatamente last - first comparações / aplicações do predicado

Original:

exactly last - first comparisons / applications of the predicate

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Possível implementação

First version
template<class InputIt, class T>typename iterator_traits<InputIt>::difference_type count(InputIt first, InputIt last, const T& value){typename iterator_traits<InputIt>::difference_type ret =0;for(; first != last;++first){if(*first == value){ ret++;}}return ret;}
Second version
template<class InputIt, class UnaryPredicate>typename iterator_traits<InputIt>::difference_type count_if(InputIt first, InputIt last, UnaryPredicate p){typename iterator_traits<InputIt>::difference_type ret =0;for(; first != last;++first){if(p(*first)){ ret++;}}return ret;}

Exemplo

O código a seguir usa count para determinar quantos números inteiros em uma std::vector corresponder a um valor alvo .

Original:

The following code uses count to determine how many integers in a std::vector match a target value.

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#include <algorithm>#include <iostream>#include <vector>   int main(){int data[]={1, 2, 3, 4, 4, 3, 7, 8, 9, 10};std::vector<int> v(data, data+10);   int target1 =3;int target2 =5;int num_items1 = std::count(v.begin(), v.end(), target1);int num_items2 = std::count(v.begin(), v.end(), target2);   std::cout<<"number: "<< target1 <<" count: "<< num_items1 <<'\n';std::cout<<"number: "<< target2 <<" count: "<< num_items2 <<'\n';}

Saída:

number: 3 count: 2 number: 5 count: 0

Este exemplo usa um lambda expressão contar elementos divisível por 3 .

Original:

This example uses a lambda expressão to count elements divisible by 3.

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#include <algorithm>#include <iostream>#include <vector>   int main(){int data[]={1, 2, 3, 4, 4, 3, 7, 8, 9, 10};std::vector<int> v(data, data+10);   int num_items1 = std::count_if(v.begin(), v.end(), [](int i){return i %3==0;});   std::cout<<"number divisible by three: "<< num_items1 <<'\n';}

Saída:

number divisible by three: 3