How to find out if an item is present in a std::vector?

Question

All I want to do is to check whether an element exists in the vector or not, so I can deal with each case.

if ( item_present )
   do_this();
else
   do_that(         


        

Answer 1

(C++17 and above):

can use std::search also

This is also useful for searching sequence of elements.

#include 
#include 
#include 

template 
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 v = {2,4,6,8};

     //THIS WORKS. SEARCHING ONLY ONE ELEMENT.
     std::vector searchVector1 = {2};
     if(search_vector(v,searchVector1))
         std::cout<<"searchVector1 found"< searchVector2 = {6,8};
     if(search_vector(v,searchVector2))
         std::cout<<"searchVector2 found"< searchVector3 = {8,6};
     if(search_vector(v,searchVector3))
         std::cout<<"searchVector3 found"<

Also there is flexibility of passing some search algorithms. Refer here.

https://en.cppreference.com/w/cpp/algorithm/search