Check if element is in the list (contains)

c++ contains
ducin picture ducin · Jun 10, 2014 · Viewed 124.1k times · Source

I've got a list of elements, say, integers and I want to check if my variable (another integer) is one of the elements from the list. In python I'd do:

my_list = [1,2,3,4] # elements
my_var = 3 # my variable
my_var in my_list # returns boolean

How to do that in C++? I thought of using std::list, but I can find no find method in it. I can see such method in std::set structure.

More deeply, the problem is that my program is given some unique ids (a list, a set, whatever) and I iterate over a long list of input data (ids) and check if they are included in the list (boolean value returned for each iteration step). And I'm not sure how should I do that in C++.

Answer

Matzi picture Matzi · Jun 10, 2014

You can use std::find

bool found = (std::find(my_list.begin(), my_list.end(), my_var) != my_list.end());

You need to include <algorithm>. It should work on standard containers, vectors lists, etc...

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