code - Some questions about operators in php?

In php (or in other languages?), similar to

<code>if(!$a=b){
    .....
}</code>

or

<code>empty($a)&&$a=array()</code>

What does

mean? What are the benefits of writing this way?

Reply content:

In php (or in other languages?), similar to

<code>if(!$a=b){
    .....
}</code>

or

<code>empty($a)&&$a=array()</code>

What does

mean? What are the benefits of writing this way?

Don’t write like this.
For example, I have been writing code for several years, and I don’t know the priority of ! and = at first glance

$a = someFunc();
if ($a) {
abc();
}

if ($a = someFunc()) {
abc();
}

if ( !($a = someFunc()) ) {
abc();
}

if ( ! $a = someFunc() ) {
abc();
}

($a = someFunc()) && abc();

Finally, use if else all the time. The code is fun for a while, but the maintenance is heartbreaking.

empty($a) && $a=array()
//这是短路运算符，如同
if(empty($a)){
   $a=array();
}

if(!$a=b){

<code>.....</code>

}
First assign value b
to $a and then!$a Just pay attention to the operator priority here

The expression before the second && is only to determine whether the variable is empty; the following expression is to determine whether it is an empty array, which can be omitted here

<code>    $a = FALSE; 
    $b = TRUE; 
    $c = 2;
    
    // $a为false，短路了，$c没有赋值20
    $a && $c=20;
    echo $c; // 2

    echo "<br />";

    // $b为true，走了下一步，$c被赋值20
    $b && $c=20;
    echo $c; // 20
</code>

Your code can be understood as: if $a does not exist, it is true, take the next step and assign a value to $a;