The set::count() is a built-in function in C++ STL which returns the number of times an element occurs in the set. It can only return 1 or 0 as the set container contains unique elements only.
Parameters: The function accepts one mandatory parameter element which specifies the element whose count is to be returned.
Return Value: The function returns 1 or 0 as the set contains unique elements only. It returns 1 if the value is present in the set container. It returns 0 if it is not present in the container.
Below is the illustration of the above function.
11 is present in the set 18 is not present in the set