I would use count() if they are the same, as in my experience it is more common, and therefore will cause less developers reading your code to say "sizeof(), what is that?" and having to consult the documentation.
I think it means sizeof() does not work like it does in C (calculating the size of a datatype). It probably made this mention explicitly because PHP is written in C, and provides a lot of identically named wrappers for C functions (strlen(), printf(), etc)
PHP
php.net › manual › en › function.count.php
PHP: count - Manual
Eg: // Bad approach for($i=0;$i<count($some_arr);$i++) { // calculations } // Good approach $arr_length = count($some_arr); for($i=0;$i<$arr_length;$i++) { // calculations } up · down · 4 lucasfsmartins at gmail dot com ¶ · 7 years ago · If you are on PHP 7.2+, you need to be aware of "Changelog" and use something like this: <?php $countFruits = is_array($countFruits) || $countFruits instanceof Countable ? count($countFruits) : 0; ?> You can organize your code to ensure that the variable is an array, or you can extend the Countable so that you don't have to do this check.
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I would use count() if they are the same, as in my experience it is more common, and therefore will cause less developers reading your code to say "sizeof(), what is that?" and having to consult the documentation.
I think it means sizeof() does not work like it does in C (calculating the size of a datatype). It probably made this mention explicitly because PHP is written in C, and provides a lot of identically named wrappers for C functions (strlen(), printf(), etc)
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According to phpbench:
Is it worth the effort to calculate the length of the loop in advance?
//pre-calculate the size of array
$size = count(
size = sizeOf(
i=0; 
size; $i++) {
//...
}
//don't pre-calculate
for (
i<count(
i++) { //or $i<sizeOf($x);
//...
}
A loop with 1000 keys with 1 byte values are given.
| count() | sizeof() | |
|---|---|---|
| With precalc | 152 | 212 |
| Without precalc | 70401 | 50644 |
(time in µs)
So I personally prefer to use count() instead of sizeof() with pre calc.
How to declare the length/size of an array in php, so users can input any size - Stack Overflow
I understand but think about this if we could declare the size say in this format $a=[12], but this means the index 0 of the array $a has a value 12 in it. But in c if we declare like $a=[12], it means it has the array $a can store 12 elements. They should avail this in php if possible, because ... More on stackoverflow.com
How do you routinely check that an array is empty?
if ($array === []) More on reddit.com
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July 12, 2021I found a website completely about finding the length of an array in PHP.
Random bit of count() trivia: Usually this function is O(1), because arrays store how many elements they contain. However, there is one exception to this: If you do count($GLOBALS) the operation is O(n), because PHP has to scan through the whole array to check for indirectly deleted elements . Now you know. More on reddit.com
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August 8, 2017PHP Code Golf: Detect if string contains an element from array.
Throughout my 6+ year career I have had to write code for checking if one or more strings exist in another string. When doing this in the past, I… More on reddit.com
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November 17, 2017How does checking the PHP array length affect performance?
Checking the php array length using count() is an extremely fast operation. PHP internally keeps track of the element count for each array, so when you call count(), it simply retrieves this stored value. This is an O(1) operation, meaning its execution time is constant and does not depend on the size of the array. Therefore, it is not a performance bottleneck, even for very large arrays.
upgrad.com
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PHP Array Length: Easy Methods to Find Array Size in PHP
What is the primary function to get the PHP array length?
The primary and most recommended function to get the php array length is count(). This built-in function is specifically designed to count all the elements in an array or the properties in an object. It is straightforward, efficient, and universally understood by PHP developers. When you need to determine the number of items in any array, count() should be your first choice.
Code Example:PHP$fruits = ["Apple", "Banana", "Cherry"];$length = count($fruits);// $length is now 3
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upgrad.com › home › blog › software development › php array length: a complete guide to finding array length in php [with examples]
PHP Array Length: Easy Methods to Find Array Size in PHP
How do I properly use the PHP array length in a for loop?
A for loop is a common use case for the php array length. You typically initialize the loop counter at 0 and have it continue as long as the counter is less than the array's length. The length is retrieved once using count() before the loop starts for optimal performance.Code Example:PHP$colors = ["Red", "Green", "Blue"];$length = count($colors);for ($i = 0; $i < $length; $i++) { echo $colors[$i] . "
";}
";}
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PHP Array Length: Easy Methods to Find Array Size in PHP
W3Schools
w3schools.com › Php › func_array_count.asp
PHP count() Function
Arrays Indexed Arrays Associative Arrays Create Arrays Access Array Items Update Array Items Add Array Items Remove Array Items Sorting Arrays Multidimensional Arrays Array Functions PHP Superglobals
ReqBin
reqbin.com › code › php › iawpnvuz › php-array-length-example
How to get the length of an array in PHP?
In this PHP Array Length example, we obtain the array's length using the count() function.
Carmatec
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How to Get the Length of an Array in PHP: Complete Guide
3 weeks ago - Here are a few best practices to follow when working with arrays and their lengths in PHP: Always prefer count() or sizeof() for clarity: Using built-in functions is not only more efficient but also more readable to others who may read your code. Use COUNT_RECURSIVE for multi-dimensional arrays: If you’re dealing with nested arrays and need to count all elements, use the COUNT_RECURSIVE mode with count(). Check if the array exists: Before getting the length of an array, ensure that the variable is an array using is_array().
Upgrad
upgrad.com › home › blog › software development › php array length: a complete guide to finding array length in php [with examples]
PHP Array Length: Easy Methods to Find Array Size in PHP
July 6, 2026 - These functions serve completely different purposes. count() is used to find length of an array in php by counting the number of elements it contains. strlen(), on the other hand, is used to find the length of a string by counting the number ...
freeCodeCamp
freecodecamp.org › news › php-array-length-how-to-get-an-array-size
PHP Array Length Tutorial – How to Get an Array Size
August 27, 2021 - By Jonathan Bossenger Arrays are a powerful data type in PHP. And knowing how to quickly determine the size of an array is a useful skill. In this article I'll give you a quick overview of how arrays work, and then I'll dive into how to get the size...
Scaler
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How to Find the Length of an Array in PHP? - Scaler Topics
April 12, 2024 - Keeping track of array length is particularly useful when dynamic manipulation of array elements occurs, ensuring that accurate and reliable operations are performed on arrays of varying sizes. In PHP, obtaining the size or length of an array is accomplished using the count() function.
FlatCoding
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How to Use PHP count() to Get Array Length - FlatCoding
June 22, 2025 - The count() function returns the number of elements in an array or a Countable object. You can use it on both indexed and associative arrays. It helps you control loops such as manage data checks and get total values.
BitDegree
bitdegree.org › learn › php-array-length
Learn About PHP Array Length: PHP Count Function Explained
August 14, 2017 - <?php $fruits = ['Banana', 'Cherry', 'Peach']; $array_length = count($fruits); echo "Result: " .
SearchHounds
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How to Get the Length of an Array in PHP
A professional website and blog help musicians control their brand, deepen fan relationships, and drive sustainable growth beyond social media. This guide covers planning, design, tech choices, SEO, and content strategies tailored to artists.
Devsheet
devsheet.com › code-snippet › get-array-length-in-php
Get array length in PHP - Devsheet
To get the length of an array in PHP you can use its inbuild function count() which takes array as a parameter and returns array length.
Top answer 1 of 3
2
In PHP you define/declare an array by just
$oldSchool = array();
$newSchool = []; // use this one!
You can add new elements to it by simply using [] next to the array as:
$array[] = 'new element';
count($array); // returns the lenght of the array
You can easily iterate an array using a foreach loop:
foreach($array as $key => $value) {
echo sprintf('key: %s, value: %s',$key, $value) . PHP_EOL;
}
There are plenty of in-build php functions to play with arrays https://www.php.net/manual/en/ref.array.php
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PHP doesn't have a concept of arrays. It has ordered maps which it calls arrays. They have no finite size. You can't have a fixed size array unless you use the SplFixedArray class
To create PHP's "array" you can use the following syntax.
$myArray = [];
To add elements you use keys. This will map one value to another.
$myArray['myKey'] = 'My string';
You can also use numerical keys or append a new value to the map.
$myArray[42] = 'My string of 42';
$myArray[] = 'Appended value'; // the key will be generated by PHP and will be the next available numerical value
Upgrad
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How to find Array Length in PHP? | upGrad blog
June 8, 2026 - To put it simply, you can use the PHP count() or sizeof() function to find out the PHP array count or a specific number of elements in an array. They are built-in functions in PHP that return the number or size of elements in their respective arrays.
Techy Hunger
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PHP Array Length: Count All Elements in an Array in PHP Techy Hunger
January 8, 2023 - If you want to count the total number of elements or values in an array, you can easily do it by using PHP inbuilt functions called count() or sizeof().
Javatpoint
javatpoint.com › how-to-count-all-elements-in-an-array-in-php
How to count all elements in an array in PHP? - javatpoint
PHP language has a GMP function called gmp_rootrem() that delivers the integer data of the Nth root of an input GMP parameter or GMP value. Syntax The syntax shows the GMP function to get a root value of the GMP parameter.
sebhastian
sebhastian.com › php-array-length
PHP how to get an array's length (single and multi-dimensional arrays) | sebhastian
November 8, 2022 - To get an array’s length in PHP, you can use either the sizeof() or count() function.
Lightly-dev
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Lightly-dev
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