constant already defined in php

Question

I have a function that I am trying to run but it shows the message as CONSTANT already defined.

I tried to put a condition saying \"if defined\" about the function

Answer 1

define()

Example:

/* Note the use of quotes, this is important.  This example is checking
 * if the string 'TEST' is the name of a constant named TEST */
if (defined('TEST')) {
    echo TEST;
}

Answer 2

Is this how you check for constants:

if (defined('TEST')) {
    echo TEST;
}

Maybe you're not doing the check properly OR the constant you are checking for isn't the cause of the error, some rogue include file might have a different constant and produces an overlap / re-definition.

Answer 3

Replace this:

define('constant', 'value');

with this:

if (!defined('constant')) define('constant', 'value');