php, infinite loop in while() loop

Question

/// infinite loop??
$x=1; 
while($x=9){ 
echo $x;
$x++;
}

i dont understand the reason behind, why the above code causes infinite loop in my opinion above code should output "9" once. but it outputs endless 999999999......

at first (when x is equal to 1) while statement is false so nothing happens, then x becomes 2 but again while statement is false;

So when x becomes 9 while statement is true so it should echo 9 then we add 1 due to x++; and it becomes 10 so while statement becomes false but as i see it doesnt because

it continues to echo 9999999.......

pls enlighten me regarding the above code. best regards.

note:i have checked the similar questions but cant find the answer for my situation thx

For this reason, you will see it written if (9 == $x) in many cases, to avoid such errors. — JRL
– JRL, Commented Sep 18, 2011 at 21:02
I think you should have assumed something was wrong from the very first moment when your x=9 made it into the while loop. If the while condition is false then $x++ wouldn't even have ran all. — Felype
– Felype, Commented Jul 17, 2015 at 17:33

Ignacio Vazquez-Abrams · Accepted Answer · 2011-09-18 21:01:07Z

10

$x=9 is an assignment, and is always true. Perhaps you meant $x==9, or some other relational operator.

answered Sep 18, 2011 at 21:01

Ignacio Vazquez-Abrams

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Comments

genesis · Accepted Answer · 2011-09-18 21:02:03Z

3

You mean

$x == 9

But in your example it won't do anything, because $x != 9. You probably mean

while($x < 9)

answered Sep 18, 2011 at 21:02

genesis

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1 Comment

Rick Over a year ago

Old thread, but in case someone reads it. The But in your example it won't do anything, because $x != 9. You probably mean while($x < 9) is untrue. If he DOES write $x == 9, then the loop while stop as soon as $x becomes 9. So it will output 123456789 and then stop.

BRampersad · Accepted Answer · 2011-09-18 22:18:31Z

1

You are assigning the value of 9 to the variable x instead of performing a relational comparison. A common mistake. = is the assignment operator whereas == is the equality comparison operator.

http://en.wikipedia.org/wiki/Assignment_(computer_science)#Assignment_versus_equality

answered Sep 18, 2011 at 22:18

BRampersad

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