PHP has a few functions for handling arrays. The most common array function is count(). This function returns the number of elements in an array.
The parameter of the count() function must be an array or an object that implements the countable interface. This is due to how the function works – it loops through each element and returns the number it finds.
If given a scalar value, such as a string or a number, it will return 1, as only one element was found. If given nothing, an error will occur. As such, check if your parameter is not null or empty before using this function!
Many beginners make the mistake of using count() on values that are not arrays or objects that implement Countable. As such, this article will discuss when you can and cannot use this helpful function.
Example of countable object
A countable object is an object that has a count() method, which returns the number of objects it contains. All arrays and instances of ArrayProxy are countable objects.
All strings (“foo”) and RegExp objects (new RegExp(“foo”)) are not countable objects as they do not have a count() method.
You can test if an object is countable by using the new Countability() prototype property of the Object prototype. If the returned value is true, then the given object is a countable object.
You can test if an object is countable by using the new Countability() prototype property of the Object prototype.
Example of a countable array
As mentioned before, an array can be created with the new Array() function. You can also create an array using the [] literal.
An array can be created using a single value or multiple values. In this example, we will use a single value. You can also create an empty array with the new Array() function or the [] literal.
var fruits = new Array(‘apple’, ‘banana’, ‘orange’); // OR var fruits = []; // OR var fruits = {‘apple’: ‘banana’};
Both of these arrays are valid and contain no values. The first one is an empty array, and the second one is an empty object that implements Countable. Both of these will be explained in more detail later in this article.
The parameter must be an array or an object that implements countable
In the latest version of PHP, the count function was added. It is called count() and takes a single parameter.
Unlike array_count_values(), it does not take an array as a parameter, but instead takes any kind of object, even arrays. It will return the number of values in that object, regardless of what type of value it is.
Although this function was intended for use with arrays only, you can pass any type of object into it and it will return the number of values within that object. This makes it very useful when dealing with custom objects as well as arrays.
Like array_count_values(), the count() function will return 0 if given an empty object. This is helpful when checking whether or not an object contains any values or not.
Compile error: cannot convert…to integer
When you try to assign a non-array value to an array, the compiler gives you a warning and replaces the non-array with its zero equivalent. For example, if you tried to assign a string to an array, the compiler would convert the string to zero length.
However, in some cases, the compiler will not allow you to assign a non-integer value to an integer index of an array. In those cases, you will get a compile error.
Arrays are strongly typed in JavaScript which helps prevent some errors before runtime. While this is helpful, it can also lead to errors that are hard to detect until your code is running. This is why constant checking of arrays is important.
Solution to the parameter issue
As of April 19, 2018, the Count() method required that the parameter be an array or an object that implemented countable. This was changed shortly after to allow any value to be passed into the parameter.
Params are now accepted as any type of value, and they are processed as an array. If no params are provided, then an empty array is created and passed into the method.
However, this change has caused some issues with older code. Many developers were not aware of this change and did not update their code to enforce it. As a result, many apps may have broken functionality due to lack of this updated requirement.
If you find your app having issues with the Count() method, check your code and see if you are passing in a non-array or non-countable object.
Summary
In this article, we discussed the importance of understanding array functions in PHP and how they can be misused. We specifically looked at the array_count_values() , array_unique() , and count() functions.
You should always test your code to ensure that it is not passing a variable that is not an array or an object that implements Countable to these functions. This will save you a lot of headaches later when you discover your errors early.
You should also always double check your output from these functions to make sure that only the appropriate values were counted or uniques values were removed.
Learning about array functions is an easy way to improve your code and reduce errors in your projects.
