Hello Monks! I have question 

my $a=1;

print ++$a + $a++;

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How much will this print?

shouldn't it be 4? And not 5?

I test this in PHP and there is 5

1. in the start $a is 1

2. first of all in the print is ++$a and $a become 2

3. second is $a+$a and become 4

4. third is print

5. fourth $a become 3

Thank you

I found the answer in perldoc

Note that just as in C, Perl doesn't define when the variable is incremented or decremented. You just know it will be done sometime before or after the value is returned. This also means that modifying a variable twice in the same statement will lead to undefined behavior. Avoid statements like: 

$i = $i ++;
    print ++ $i + $i ++;

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In reply to Question preincrement by himik

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