I was reading the PHP documentation and a function is_scalar() - as said by the site itself - when it is used it will inform if a certain variable is scalar. However, I wanted to know more about these scalar variables:
The simplest answer is that this term, which is used not only with PHP but as with most other languages, comes from linear algebra.
In linear algebra, we say that a value is scalar to denote a simple number or value, not an algebraic structure. Talking about the algebraic structures themselves would kind of divert the subject, so for the curious I'll just leave a link to the corresponding wiki of the Algebraic structure .
In programming, a variable is scalar if it is a number, a string or another type of so-called "primitives" in several languages - which is distinct from a more logical structure and set of implicit operations as an instance of a class or an array . And yes, I know that strings are in the background arrays of characters, but receive special treatment in almost every language.
A scalar variable is a simple value such as an int , float , string , boolean . This type can be accessed / manipulated without any additional instruction, just call it, other than an array or some other you have to specify the element or key.
Non-scalar types are composed or need something more to be manipulated as objects, arrays and resources.
An example of a common error is trying to print a composite type:
$arr = array('nome' => 'Fulano');
echo $arr; // Notice: Array to string conversion
//O correto seria especificar qual elemento do array deseja manipular. Por exemplo:
echo $arr['nome'];