c++stdstdvector

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

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();
Solution

  • You can use std::find from <algorithm>:

    #include <algorithm>
#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()

    This returns an iterator to the first element found. If not present, it returns an iterator to one-past-the-last. With your example:

    #include <algorithm>
#include <vector>

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