即使在声明之后，变量也是未定义的

Question

My ONE,TWO, and THREE variables are undefined when I try and run the script even though it's defined in the global scope. My A,B, and C variables are considered defined though. At first I thought it was because I'm assigning constant values as keys, but I didn't find anything online that said I couldn't do that.

<?php class aClass
{


    const A = 1;
    const B = 2;
    const C = 3;

    const ONE = 1;
    const TWO = 2;
    const THREE = 3;
    public $arr = [];


    function __construct() {

        $this->createArray();

    }



    function createArray() {

        $this->arr[] = $this->A = [
            $this->ONE => 'one.',
            $this->TWO => 'two',
            $this->THREE => 'three'
            ];

        $this->arr[] = $this->B = [
            $this->ONE => 'one',
            $this->TWO => 'two',
            $this->THREE => 'three',
            ];

        $this->arr[] = $this->C = [
            $this->ONE => 'one',
            $this->TWO => 'two',
            $this->THREE => 'three',
            ];


    }
}


?>

Answer 1

You do need to change the constants in createArray from $this=> to self::, but that change alone should result in a syntax error:

$this->arr[] = self::A = [
    self::ONE => 'one.',
    self::TWO => 'two',
    self::THREE => 'three'
];

will get you a

Parse error: syntax error, unexpected '='

at this line:

$this->arr[] = self::A = [`
//                this ^ is the unexpected =

You mentioned using constant values as keys, which is what you're doing with

self::ONE => 'one.'

but is not what you're doing with

$this->arr[] = self::A = [ ...

With that line, you're not using self::A as a key, you're actually assigning the following array to self::A (which causes the "unexpected '='" error, because you can't assign things to constants), then assigning self::A to $this->arr[].

If you want to use self::A as a key in $this->arr, you'll need to do it like this instead:

$this->arr[self::A] = [
    self::ONE => 'one.',
    self::TWO => 'two',
    self::THREE => 'three'
];