PHP count() Function

Syntax

The count() function is used to count the number of elements in an array. It has the following syntax:

count(array, mode)

• array: The array whose elements you want to count.
   
• mode (optional): It can take the following values:
  • 0 (default): Counts only the elements in the first level of the array.
  •  
  • 1: Counts elements recursively, including elements inside sub-arrays.

Example

$numbers = array(1, 2, 3, 4, 5);
echo count($numbers); 

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Output: 

5

Using count() with Multidimensional Arrays

If an array contains sub-arrays, the count() function, by default, does not count the elements inside those sub-arrays. However, by passing 1 as the second argument, we can count all elements recursively.

$multiArray = array(
    array(1, 2, 3),
    array(4, 5, 6),
);

echo count($multiArray); 
echo count($multiArray, 1); 

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Output

2
8

Example: Counting Elements in Different Types of Arrays

Let's take a look at a few more examples of how count() works with different arrays.

Example 1: Counting Elements in an Indexed Array

$fruits = array("Apple", "Banana", "Orange", "Mango");
echo count($fruits); 

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Output: 

4

Example 2: Counting Elements in an Associative Array

$person = array("name" => "John", "age" => 25, "city" => "New York");
echo count($person); 

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Output:

3

Example 3: Counting Elements in a Nested Array

$data = array(
    "students" => array("Alice", "Bob", "Charlie"),
    "teachers" => array("Mr. Smith", "Ms. Johnson"),
);

echo count($data); 
echo count($data, COUNT_RECURSIVE); 

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Output: 

2 (Counts only main keys)
5 (Counts all elements inside sub-arrays)

Difference Between count() and sizeof() Methods

PHP provides two functions to count elements in an array: count() and sizeof(). These two functions are nearly identical in behavior, but there are slight differences in how they are used.

Example: count() vs sizeof()

$array = array("one", "two", "three", "four");

echo count($array); 
echo sizeof($array); 

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Output:

4
4

Example: Using count() in Recursive Mode

$nestedArray = array(
    array("A", "B"),
    array("C", "D"),
);

echo count($nestedArray, COUNT_RECURSIVE); 
echo sizeof($nestedArray); 

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Output: 

6
2 (Does not support recursion)

From the above examples, we can see that sizeof() is just an alias for count() but does not support recursive counting. Therefore, count() is preferred in most cases.

Frequently Asked Questions

What is the difference between count() and sizeof() in PHP?

Both count() and sizeof() return the number of elements in an array. However, count() supports recursive counting when used with mode 1, while sizeof() does not.

How do I count all elements, including nested arrays?

You can use count($array, COUNT_RECURSIVE) to count elements in a multidimensional array, including elements inside nested arrays.

Can count() be used with objects?

Yes, count() can be used with objects that implement the Countable interface. Otherwise, it will return 1 for non-iterable objects.

Conclusion

In this article, we learned about the PHP count() function, which helps in counting elements in an array or an object. We explored its usage, parameters, and how it handles different cases. Understanding this function makes working with arrays easier and more efficient. Using count() correctly improves code readability and helps manage data effectively in PHP applications.