I have come across the definition of associative arrays which are vectors with indices consisting of strings , example:
$site['nome'] = "Stack Overflow";
What are the advantages of using this kind of vectors? Since you can not use them in a repeat structure, this can be a demerit of using this kind of array . This method would be the way to do a struct or dictionary in PHP?
According to the manual , the associative arrays PHP are "ordered maps". There are a multitude of situations in which they may be useful.
The premise is not correct, you can use it in a seamless repeat structure:
$teste = array( 'banana' => 'fruta', 'alface' => 'verdura' );
foreach( $teste as $key => $value ) {
echo "$key é $value<br>\n";
}
There are numerous situations where using associative arrays makes life easier. One of them, for example, is in the return of a line from a DB.
It's much easier to understand code with $campos['nome'] , $campos['idade'] ... than $campos[1] , $campos[2] ...
In addition, if you use numeric indexes in this case, it creates an immense confusion in the code each time you add or remove a field from your original query .
In PHP especially, there are many functions to work with associative arrays , both working with key and value, as well as each of the parts separately.
Another use where associative arrays are key, is when you need to work with JSON.
Of course, this here:
"phoneNumbers": [
{
"type": "home",
"number": "212 555-1234"
},
{
"type": "office",
"number": "646 555-4567"
}
It can be represented like this:
array( "phoneNumbers" =>
array(
array( "type" => "home", "number" => "212 555-1234" ),
array( "type" => "office", "number" => "646 555-4567" )
)
)
and vice versa. PHP already has native functions that convert one format to another.
Within the primary function for which it was designed, PHP naturally uses associative arrays to receive the HTML form data, and query string data, usually through the variables $_POST and $_GET , among others.
This here:
<input type="text" name="batatinha">
When it is received by PHP, it already becomes this:
$_POST['batatinha']
or in this, depending on the method:
$_GET['batatinha']
More practicality is even harder to imagine. This applies to many other situations, such as sending files, for example.
Imagine if we had to count how many fields the form has, to sequentially access this information.
In fact they can have multiple data types with keys, not just strings .
Its main characteristic is that the data is stored sparse, that is, it does not follow a continuous sequence, such as common arrays . Obviously this has its drawbacks there.
It really is a dictionary, also called a hash table or value map. It is used to simulate struct , since PHP has nothing similar. Some will say that a class can simulate a struct . That's true, but what most people do not know is that the class in PHP is an associative array form. It is not a simple structure and continues as it is in C or other typically static languages.
It can be used in a sim repeat structure. It can access all values one by one. Only your internal organization is different.
In PHP it is used extensively to receive data that arrives externally from the web server or by a query to the database.