Who can explain in detail the PHP $a = 10; $b = $a--+--$a; Implementation process?

Who can explain in detail the PHP $a = 10; $b = $a--+--$a; Implementation process?

When I was reading Gaulo's book, "PHP," I Found

$a = 10;$b = $a++ + ++$a;    //书上写的执行过程是$a先自增1后再自增1，再赋给$becho $a;       //$a = 12;echo $b;       //$b = 22;$b = $a-- - --$a;   //$a先自增1后再自增1，再赋给$becho $a;       //$a = 10echo $b;       //$b = 2

If it's logical, then add

$b = $a-- + --$a;echo $a;       //$a = 8;echo $b;       //$b = 18;

Can someone please tell me the detailed execution of this code?

Reply content:

Who can explain in detail the PHP $a = 10; $b = $a--+--$a; Implementation process?

When I was reading Gaulo's book, "PHP," I Found

$a = 10;$b = $a++ + ++$a;    //书上写的执行过程是$a先自增1后再自增1，再赋给$becho $a;       //$a = 12;echo $b;       //$b = 22;$b = $a-- - --$a;   //$a先自增1后再自增1，再赋给$becho $a;       //$a = 10echo $b;       //$b = 2

If it's logical, then add

$b = $a-- + --$a;echo $a;       //$a = 8;echo $b;       //$b = 18;

Can someone please tell me the detailed execution of this code?

Sweat, the three pieces of code are the same, it is necessary to put so much? Whether it is $a++ or not ++$a , you just have to understand that it's better to read the code from left to right.

$a++The value of the first is $a taken out, and then self-added 1, so the $b = $a++; result of the output should be$a=11;$b=10;

++$aThe meaning is to do the $a self-add 1, and then the $a value is taken out, so $b = ++$a; the result of the output should be$a = 11;$b=11;

If you can understand the above two paragraphs, it is not a problem to understand your calculation according to this idea. I'll tell you the last one:

$b = $a-- + --$a;

This should be broken down for easy understanding.

$c = $a--;$d = --$a;$b = $c + $d;

As explained above, the $a-- value is returned here $a , and then the $a self minus 1, at this point $a=9;$c=10; . --$ahere is the $a self minus 1 and then $a the return value, so at this point $a=8;$d=8; . The final result is naturally $a=8;$b=18; .

