How to understand this formula (DEBUG_MODE 2) = 2)

How to understand this formula (DEBUG_MODE & 2) = 2)

(DEBUG_MODE & 2) = 2) // if this sentence is to be set up, it must be (2 & 2) = 2). How can this statement be understood?
Define ('debug _ mode', false); // if it is 2, 1 is displayed.

If (DEBUG_MODE & 2) = 2)

{

$ Smarty = '1 ';

}

Else

{

$ Smarty = '0 ';

}

Echo $ smarty;

?>

Copy code []


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"= &" What is this operator?
$ User = & init_users ();
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Yes, but I do not know what to use in front of the function.
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Bitwise operations and operations...
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Let me explain it.

In fact, here 2 should be a fixed value, which is a constant that defines your mode. If you write it like this, it will be easy to understand.

Define ('mode _ a', 2 );

$ Now_mode = 2;



If ($ now_mode & MODE_A) = MODE_A ){

Echo "the current mode is MODE_A ";

}

?>


Some students copied the code and said, why don't you use = for direct judgment? In fact, there is also a meaning of the contained relationship.
For example, the value of 6 & 2 is 2, and the value of 6 & 3 is 2, and the value of 2! = 3
This method usually represents a range. Let's take a look at the relationship between the IP address and the subnet mask in the computer network.
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Thanks. LS. Your answer is easy to understand.
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Original Post published by lmhllr at [url = http://www.111cn.cn/bbs/redirect.php? Goto = findpost & pid = 335104 & ptid = 46748] link mark [img] http://www.111cn.cn/bbs/images/common/back.gif?/img=#/url]
Bitwise operations and operations...
Can you explain his role? I still don't understand the intention of this writing.
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Original Post published by jayliu at [url = http://www.111cn.cn/bbs/redirect.php? Goto = findpost & pid = 335044 & ptid = 46748] link mark [img] http://www.111cn.cn/bbs/images/common/back.gif?/img=#/url]
Yes, but I do not know what to use in front of the function.
Added &
Function return value is reference

Php5 is referenced by default and cannot be used in disorder. In php5, if the function returns false directly, the function with & is suspended, and php cannot find the referenced address.
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I have learned new things from LS. Thanks to [img] http://www.111cn.cn/bbs/images/smilies/default/policy.gif#/img].
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It turns out like this.