PHP string comparison with zero

Question

I need to write an if condition to detect blank string on PHP. But the variable may get numbers also. So I write the condition like follows. While the variable get the value zero "0" as number the condition detect it as blank ""

$string = array_search("value match", $array);   //$string = 0;

if($string == "")
{
    echo "not equal";
}

Is it a bug on PHP? How we can detect for blank value (not null) for a variable which may have numbers or string?

$string is not a string but an integer. And that 0 == "" is intended behavior. — Gumbo
– Gumbo, Commented Nov 30, 2014 at 18:19
For further detail following is the function used to get the value of variable $string = array_search("value match", $array);. If there is no search match i have to detect it by if condition. — sugunan
– sugunan, Commented Nov 30, 2014 at 18:29
@SmokeyPHP: yes it works $string === false then how 0 escape from equal to false?. Any how your idea works for my requirement. Thank you. — sugunan
– sugunan, Commented Nov 30, 2014 at 18:35

Liglo App · Accepted Answer · 2014-12-03 14:20:00Z

4

Try this:

if ($string === "") { //With three equality signs
}

That's because both 0 and "" evaluates to empty(). It's not a bug, but a side effect of loose typing.

edited Dec 3, 2014 at 14:20

answered Nov 30, 2014 at 18:21

Liglo App

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3 Comments

sugunan Over a year ago

This fail to detect ""

Liglo App Over a year ago

How comes? It's a direct comparison to "" ("" === "" will return true, of course), how can it fail? It will not detect 0, however. For this, you have to use $string === 0 which will check, if $string is a number and exactly 0.

sugunan Over a year ago

Following is the function i used to get value $string = array_search("value match", $array);. If there is no search match I have to detect it by if condition.

MDEV · Accepted Answer · 2014-11-30 18:38:24Z

2

When using array_search you will need to check for false:

if($string !== false) //Note !== rather than != (stops 0 equating to false)

Otherwise 0 will be treated as 'falsy', even though it's a valid return value (first element/key)

answered Nov 30, 2014 at 18:38

MDEV

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1 Comment

sugunan Over a year ago

This is correct I thing small modification needed to match the code in question like follows if($string === false). Thanks for the working solution and the proper explanation.

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