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Variables

A variable is a named area of data storage that has a type and a value. Distinct variables may have the same name provided they are in different scopes. A constant is a variable that, once initialized, its value cannot be changed. Based on the context in which it is declared, a variable has a scope.

The following kinds of variable may exist in a script:

Local Variables​

Except for function parameters, a local variable is never defined explicitly; instead, it is created when it is first assigned a value. A local variable can be assigned to as a parameter in the parameter list of a function definition or inside any compound statement. It has function scope.

Consider the following example:

function do_it(bool $p1): void {
  $count = 10;
  // ...
  if ($p1) {
    $message = "Can't open file.";
    // ...
  }
  // ...
}

function call_it(): void {
  do_it(true);
}

Here, the parameter $p1 (which is a local variable) takes on the value true when do_it is called. The local variables $count and $message take on the type of the respective value being assigned to them.

Consider the following example:

function f(): void {
  $lv = 1;
  echo "\$lv = $lv\n";
  ++$lv;
}

<<__EntryPoint>>
function main(): void {
  for ($i = 1; $i <= 3; ++$i)
    f();
}

In this example, the value of the local variable $lv is not preserved between the function calls, so this function f outputs "$lv = 1" each time.

Array Elements​

An array is created via a vec-literal, a dict-literal, a keyset-literal. At the same time, one or more elements may be created for that array. New elements are inserted into an existing array via the simple-assignment operator in conjunction with the subscript [] operator.

The scope of an array element is the same as the scope of that array's name.

$colors1 = vec["green", "yellow"];   // create a vec of two elements
$colors1[] = "blue";                 // add element 2 with value "blue"
$colors2 = dict[];                   // create an empty dict
$colors2[4] = "black";               // create element 4 with value "black"

Instance Properties​

These are described in the class instance properties section. They have class scope.

Static Properties​

These are described in the class static properties section. They have class scope.

Class and Interface Constants​

These are described in the class constants section. They have class or interface scope.