What is a namespace in PHP?
Friendly reminder about namespaces… Including or requiring a PHP file that defines as namespace means that the namespace name (or its “use as …” alias) is always necessary to make use of the included file’s content:
What is the difference between require and require_once in PHP?
require_once. The require_once statement is identical to require except PHP will check if the file has already been included, and if so, not include (require) it again. See the include_once documentation for information about the _once behaviour, and how it differs from its non _once siblings.
What is the path for nested require_once () in PHP?
The path for nested require_once () is always evaluated relative to the called / first file containing require_once (). To make it more flexible, maintain the include_path (php.ini) or use set_include_path () – then the file will be looked up in all these locations.
Is it possible to build a large PHP file without require_once?
This function can be recursive, thus building up a large PHP file with no require_once references at all. The speedup can be dramatic. On one of our pages that included 115 classes, the page was sped up by 60%.
Namespaces are qualifiers that solve two different problems: They allow for better organization by grouping classes that work together to perform a task. They allow the same name to be used for more than one class.
What is the use of constant () in PHP?
A constant is an identifier (name) for a simple value. The value cannot be changed during the script. A valid constant name starts with a letter or underscore (no $ sign before the constant name). Note: Unlike variables, constants are automatically global across the entire script.
Which of the following elements are affected by namespaces in PHP?
Although any valid PHP code can be contained within a namespace, only the following types of code are affected by namespaces: classes (including abstracts and traits), interfaces, functions and constants. Namespaces are declared using the namespace keyword.
What are PHP Magic constants?
Magic constants are the predefined constants in PHP which get changed on the basis of their use. They start with double underscore (__) and ends with double underscore. They are similar to other predefined constants but as they change their values with the context, they are called magic constants.
What are constants examples?
In mathematics, a constant is a specific number or a symbol that is assigned a fixed value. In other words, a constant is a value or number that never changes in expression. Its value is constantly the same. Examples of constant are 2, 5, 0, -3, -7, 2/7, 7/9 etc.
What is difference between variable and constant in PHP?
In PHP, the constant is an identifier or a name for a simple value. In PHP, the variable is a name or symbol which stands for value and used to store values such as characters, numeric, character string and memory addresses.
What is constant array in PHP?
Yes, You can define an array as constant. From PHP 5.6 onwards, it is possible to define a constant as a scalar expression, and it is also possible to define an array constant. It is possible to define constants as a resource, but it should be avoided, as it can cause unexpected results.
Where do I put constants in PHP?
Define your constant in your top . php file, that will be included in all the other scripts. It may be your front controller, your config file, or a file created for this single purpose.
Which types are supported in PHP namespaces?
A namespace can contain valid PHP code. Namespace affects following types of code: classes (including abstracts and traits), interfaces, functions, and constants. Namespaces are declared using the namespace keyword.
Can a constant name be an empty string in PHP?
The constant name can be an empty string. As of PHP 5.4.6 constant () pays no attention to any namespace aliases that might be defined in the file in which it’s used. I.e. constant () always behaves as if it is called from the global namespace. This means that the following will not work:
How do I access the current namespace in PHP?
PHP supports two ways of abstractly accessing elements within the current namespace, the __NAMESPACE__ magic constant, and the namespace keyword. The value of __NAMESPACE__ is a string that contains the current namespace name.
What is the value of__namespace__?
The value of __NAMESPACE__ is a string that contains the current namespace name. In global, un-namespaced code, it contains an empty string. The namespace keyword can be used to explicitly request an element from the current namespace or a sub-namespace.
What is the use of constant () function in PHP?
This function works also with class constants . The constant name. Returns the value of the constant. An Error exception is thrown, if the constant is not defined. Prior to PHP 8.0.0, an E_WARNING level error was generated in that case.