常量已在 php 中定义

constant already defined in php

提问by JDesigns

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

我有一个我正在尝试运行的函数，但它显示的消息已定义为 CONSTANT。

I tried to put a condition saying "if defined" about the function but still nothing. Is there any method to ignore this and see the output?

我试图添加一个条件，说“如果已定义”关于该函数，但仍然没有。有什么方法可以忽略它并查看输出吗？

回答by OZ_

Replace this:

替换这个：

define('constant', 'value');

with this:

有了这个：

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

回答by Phill Pafford

define()

定义（）

Example:

例子：

/* 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;
}

回答by Jakub

Is this how you check for constants:

这是您检查常量的方式：

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.

也许您没有正确进行检查，或者您正在检查的常量不是错误的原因，某些流氓包含文件可能具有不同的常量并产生重叠/重新定义。