count

count(p, itr) -> Integer

Count the number of elements in itr for which predicate p returns true.

Examples

Count the number of elements satisfying a predicate:

julia> count(x -> x > 5, [1, 10, 2, 8, 7, 3])
3

This example counts the number of elements in the array that are greater than 5.

julia> count(iseven, [1, 2, 3, 4, 5, 6])
3

Here, the count function is used to count the number of even elements in the array.

julia> count(isequal("apple"), ["apple", "banana", "orange", "apple"])
2

In this case, the count function is used to count the occurrences of the string "apple" in the array.

Common mistake example:

julia> count(x -> x > 5, [])
0

When applying count on an empty collection, the result will be 0. It is important to handle this case to avoid potential errors.

julia> count(x -> x > 5, [1, 2, 3, 4, 5])
0

If there are no elements satisfying the predicate, the count will also be 0. Ensure that the predicate matches the elements you are trying to count.

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