The basic count function
The count
function in it's simplest form is used to count the number of elements in an array.
The $fruit
array contains 2 elements: 'apples' and 'oranges'. The count function in this case returns the value 2.
It also functions as you would expect with an associative array:
The $scores
array contains 3 keyvalue pairs, the count
function for the above example returns 3.
Note that NULL
values are also counted i.e the count
function does not validate the actual values, it only returns the number of values.
Counting values in an array
PHP also has a related count function for arrays array_count_values
.
The array_count_values function counts the number of occurrances of each string or integer in an array.
The array_count_values
function returns an associative array,
the keys are the values of the input array and the values are their count, e.g: a
is 2
and b
is 1
.
Note that the array_count_values
function can only count string and integer values.
The above example results in array_count_values(): Can only count STRING and INTEGER values!
Count of unique values
The array_unique function returns the unique values of an array, i.e duplicate array values are removed.
The array_unique
example below removes the duplicate 'a' value.
The array_unique
function also works on associative arrays.
This is not the same as the count of unique array values.
The unique values in the $letters
array above, are: b
and c
.
While the unique values in the $food
array, are: banana
and carrot
.
For us to find the count of unique values in an array, we can use a combination of count
, array_filter and array_count_values
.
Let's use the $letters
array as our example, we first use array_count_values
to return the count of each value in the array:
We can see from the output above that the unique letters are b
and c
.
Now we can use array_filter
to keep the values which are equal to 1.
And finally count
those values:
Counting duplicate array values
We can easily find the count of duplicate array values using a combination of count
and array_unique
.
We can count the original number of array values and subtract the number of unique array values, here are a few examples:
Count a specific value
To count a specific array value, we can use count
and array_filter
.
We'll use array_filter
with a function to keep the value we want to count and then use count
to return the number of values.
Counting a specific value using
array_filter
is roughly the equivalent of
count if, our function is the
if which determines what values are returned and then counted.
Array count vs sizeof
The sizeof function is an alias of the count function.
The sizeof function in PHP does not return the amount of memory allocated by a variable, as with other languages.
Key Takeaways
 We can use the
count
function to return the number of values in an array.
 The
array_count_values
function counts the number of occurances of each value in an array.

array_unique
removes duplicate values in an array.

array_filter
works with a callback function to filter out values from an array.
 The
sizeof
function is simply an alias of count
.