如何找出std :: vector中是否存在项目？

#1 楼

#include <vector>
vector<int> vec; 
//can have other data types instead of int but must same datatype as item 
std::find(vec.begin(), vec.end(), item) != vec.end()

#include <algorithm>
#include <vector>

if ( std::find(vec.begin(), vec.end(), item) != vec.end() )
   do_this();
else
   do_that();

#2 楼

#3 楼

#include <algorithm>
#include <vector>

using namespace std;
int main()
{   
    typedef vector<int> IntContainer;
    typedef IntContainer::iterator IntIterator;

    IntContainer vw;

    //...

    // find 5
    IntIterator i = find(vw.begin(), vw.end(), 5);

    if (i != vw.end()) {
        // found it
    } else {
        // doesn't exist
    }

    return 0;
}

#4 楼

if(std::find(vector.begin(), vector.end(), item)!=vector.end()){
      // Found the item
}

if(binary_search(vector.begin(), vector.end(), item)){
     // Found the item
}

#5 楼

#include <algorithm>


template <typename T> 
const bool Contains( std::vector<T>& Vec, const T& Element ) 
{
    if (std::find(Vec.begin(), Vec.end(), Element) != Vec.end())
        return true;

    return false;
}

if (Contains(vector,item))
   blah
else
   blah

#6 楼

if (any_of(v.begin(), v.end(), bind(equal_to<string>(), _1, item)))
   do_this();
else
   do_that();

if (any_of(v.begin(), v.end(), [&](const std::string& elem) { return elem == item; }))
   do_this();
else
   do_that();

#7 楼

template <class Container> 
const bool contains(const Container& container, const typename Container::value_type& element) 
{
    return std::find(container.begin(), container.end(), element) != container.end();
}

#8 楼

#9 楼

#10 楼

#include <boost/algorithm/cxx11/any_of.hpp>

bool item_present = boost::algorithm::any_of_equal(vector, element);

#11 楼

#include <algorithm>
#include <vector>

// You can use class, struct or primitive data type for Item
struct Item {
    //Some fields
};
typedef std::vector<Item> ItemVector;
typedef ItemVector::iterator ItemIterator;
//...
ItemVector vtItem;
//... (init data for vtItem)
Item itemToFind;
//...

ItemIterator itemItr;
itemItr = std::find(vtItem.begin(), vtItem.end(), itemToFind);
if (itemItr != vtItem.end()) {
    // Item found
    // doThis()
}
else {
    // Item not found
    // doThat()
}

#12 楼

std::find(vector.begin(), vector.end(), item) != vector.end()

#13 楼

int t=count(vec.begin(),vec.end(),item);

#14 楼

    struct isEqual
{
    isEqual(const std::string& s): m_s(s)
    {}

    bool operator()(OIDV* l)
    {
        return l->oid == m_s;
    }

    std::string m_s;
};
struct OIDV
{
    string oid;
//else
};
VecOidv::iterator itFind=find_if(vecOidv.begin(),vecOidv.end(),isEqual(szTmp));

#15 楼

#include <algorithm>
#include <iostream>
#include <vector>

template <typename Container>
bool search_vector(const Container& vec, const Container& searchvec)
{
    return std::search(vec.begin(), vec.end(), searchvec.begin(), searchvec.end()) != vec.end();
}

int main()
{
     std::vector<int> v = {2,4,6,8};

     //THIS WORKS. SEARCHING ONLY ONE ELEMENT.
     std::vector<int> searchVector1 = {2};
     if(search_vector(v,searchVector1))
         std::cout<<"searchVector1 found"<<std::endl;
     else
         std::cout<<"searchVector1 not found"<<std::endl;

     //THIS WORKS, AS THE ELEMENTS ARE SEQUENTIAL.
     std::vector<int> searchVector2 = {6,8};
     if(search_vector(v,searchVector2))
         std::cout<<"searchVector2 found"<<std::endl;
     else
         std::cout<<"searchVector2 not found"<<std::endl;

     //THIS WILL NOT WORK, AS THE ELEMENTS ARE NOT SEQUENTIAL.
     std::vector<int> searchVector3 = {8,6};
     if(search_vector(v,searchVector3))
         std::cout<<"searchVector3 found"<<std::endl;
     else
         std::cout<<"searchVector3 not found"<<std::endl;
}

#16 楼

template <typename T> bool IsInVector(const T & what, const std::vector<T> & vec)
{
    return std::find(vec.begin(),vec.end(),what)!=vec.end();
}

#17 楼

template <typename Container, typename T = typename std::decay<decltype(*std::begin(std::declval<Container>()))>::type>
bool contains(Container && c, T v)
{
    return std::find(std::begin(c), std::end(c), v) != std::end(c);
}

#18 楼

bool exists_linear( INPUT_ITERATOR first, INPUT_ITERATOR last, const T& value )

bool exists_binary( INPUT_ITERATOR first, INPUT_ITERATOR last, const T& value )

include <newton/algorithm/algorithm.hpp>

if ( newton::exists_linear(first, last, value) )
   do_this();
else
   do_that();