Defining and using variables in IF condition

Question

Is it possible to define a variable in an IF condition, and then use that variable in the same IF condition? My test shows it cannot, however, why it isn't possible escapes me. If so, how? If not, why?

function getX(){return 123;}
function getY($x){return $x*2;}
function getZ($y){return $y*2;}

if(
    true
    && $x=getX()
    && $y=getY($x)
    && $z=getZ($y)
)
    {echo('true '.$x.' '.$y.' '.$z);}
else {echo('false '.$x);}

Operators precedence?

Alma Do
– Alma Do

2014-01-13 14:48:15 +00:00
Commented Jan 13, 2014 at 14:48 — Alma Do
– Alma Do, Commented Jan 13, 2014 at 14:48

rusben · Accepted Answer · 2014-01-13 14:47:32Z

1

Add brackets () to your conditions.

function getX(){return 123;}
function getY($x){return $x*2;}
function getZ($y){return $y*2;}

if(
    true
    && ($x = getX())
    && ($y=getY($x))
    && ($z=getZ($y))
)
    {echo('true '.$x.' '.$y.' '.$z);}
else {echo('false '.$x);}

Working 3v4l: http://3v4l.org/lt3cc

answered Jan 13, 2014 at 14:47

rusben

6461 gold badge6 silver badges13 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

user1032531 Over a year ago

Good call. Can you explain what is actually happening without the brackets?

rusben Over a year ago

Well. Sorry. the comment is off toppic. PHP is not compiled. Is interpreted.

user1032531 Over a year ago

Wasn't questioning the use of "compiler" versus "interpreter". Your answer fixed the problem. Do you know why doing so works?

rusben Over a year ago

If you want be fully documented on the php interpreter, you can find here the source code. github.com/php/php-src I do not know how it completly works, sorry.

ghousseyn Over a year ago

I think it has to do with the expression evaluation. If you try one assignment alone it should work but once you add others the interpreter will get confused about what you're trying to do. You'll need to dig deeper if you want to understand the internals of thisbehavior i.e looknig into php source code

ghousseyn · Accepted Answer · 2014-01-13 14:49:45Z

1

You need to wrap your assignments within the condition into brackets like this:

function getX(){return 123;}
function getY($x){return $x*2;}
function getZ($y){return $y*2;}

if(
    true
    && ($x=getX())
    && ($y=getY($x))
    && ($z=getZ($y))
)
    {echo('true '.$x.' '.$y.' '.$z);}
else {echo('false '.$x);}

Hope this helps

answered Jan 13, 2014 at 14:49

ghousseyn

924 bronze badges

Collectives™ on Stack Overflow

Defining and using variables in IF condition

2 Answers 2

5 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

5 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related