PHP: undefined constant while defining it

2018-06-24 17:27:24

I'm getting the following error in PHP:

Notice: Use of undefined constant CONSTANT

on the exact line where I define it:

define(CONSTANT, true);

What am I doing wrong? I defined it, so why does it say "Undefined constant"?

你需要引用成为常量的字符串

define('CONSTANT', true);

The best way to understand what are you doing wrong is to read PHP manual.

Here is definition of define function.

bool define ( string $name , mixed $value [, bool $case_insensitive = false ] )

So the first argument must be a string.

If you write it like that you are using the value of an already defined constant as a constant name.

What you want to do is to pass the name as a string:

define('CONSTANT', true);

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