Regarding if statements in PHP

Question

I've seen some PHP statements that go something like

 if($variable) {} or
 if(function()) {} (if statements that don't compare two variables)

and I know they roughly mean if a function executes or if this variable exists but I can't seem to find any information on how they work specifically. Can anybody shed some light on this?

Does PHP have [anonymous functions](http://php.net/manual/en/functions.anonymous.php)? — Jared Farrish, Jul 02 '11 at 00:37
the latest 5.3 does => http://php.net/manual/en/functions.anonymous.php. I have never seen the in if statements by the way in any language... — Alfred, Jul 02 '11 at 00:39
I'm an old fogey (in internet years), and PHP *does not*, er, does have anonymous functions as of 5.3.0. — Jared Farrish, Jul 02 '11 at 00:40
with function() do you mean a generic func(); or the reserved word function ? — dynamic, Jul 02 '11 at 00:41
@Alfred - You do realize that was the link I had in my original comment? — Jared Farrish, Jul 02 '11 at 00:41
@Jared I did not realize that.. I also don't believe you had that in beginning and edited your question 6 minutes ago.. — Alfred, Jul 02 '11 at 00:44
@Alfred - I did edit my *comment* (I am not the OP), but it was almost immediately after I posted my comment. Either way, it doesn't matter. I'm old school. :) — Jared Farrish, Jul 02 '11 at 00:47
@Alfred - Anonymous functions in PHP is like plastic wrap on a sailboat. I guess I just don't get it... — Jared Farrish, Jul 02 '11 at 00:53

score 7 · Accepted Answer · answered Jul 02 '11 at 00:38

7

if(function()) {} means if the function function's return value is true or true-like then the block will execute.

answered Jul 02 '11 at 00:38

logicbloke · Answer 2 · 2021-01-20T19:27:01.307

2

If a variable is equal to a number which is not zero, that's considered as true. as well as if the function returns a positive/negative number which is different from 0.

edited Jan 20 '21 at 19:27

answered Jul 02 '11 at 00:39

logicbloke

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score 2 · Answer 3 · answered Jul 02 '11 at 00:40

From the PHP manual:

if (expr) statement

As described in the section about expressions, expression is evaluated to its Boolean value. If expression evaluates to TRUE, PHP will execute statement, and if it evaluates to FALSE - it'll ignore it.

So, if a function successfully runs (true) or a variable exists (true) the if statement will continue. Otherwise it will be ignored.

score 1 · Answer 4 · answered Jul 02 '11 at 00:38

1

The if statements determine whether the given variable is true or a given function returns true. A variable is considered "true" if it isn't null, false, 0, or (perhaps) an empty string.

answered Jul 02 '11 at 00:38

Peter O.

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score 1 · Answer 5 · answered Jul 02 '11 at 00:41

When PHP evaluates if statements, it is determining whether or not the contents are true. It considers anything other than 0 to be true, and 0 to be false. This means you can put a function in there that returns anything and based on that it will determine whether or not to execute the contents of the if block.

score 1 · Answer 6 · answered Jul 02 '11 at 02:43

something that may help. You are probably thinking of something like if ($variable < 10), or if ($variable == 'some value'). Just like +, -, /, *, and % these are operators. 1 + 3 returns a value of 4 which is used in the rest of a standard statement. 1 < 3 returns a value of false which is used in the rest of the statement. the if-method accepts a boolean parameter, and executes code if that boolean parameter is true.

notice that:

if (1 < 3) { ... }

is the same as

$myComparison = 1 < 3;
if ($myComparison) { ... }

Regarding if statements in PHP

6 Answers6

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