CODEWITHSUNDEEP
phpstrpos
Daniel
Daniel

Reputation: 315

Why does strictly comparing strpos() against true give the opposite intended result?

Why isn't this standalone code working:

$link = 'https://google.com';
$unacceptables = ['https:','.doc','.pdf', '.jpg', '.jpeg', '.gif', '.bmp', '.png'];

foreach ($unacceptables as $unacceptable) {
    if (strpos($link, $unacceptable) === true) {
        echo 'Unacceptable Found<br />';
    } else {
        echo 'Acceptable!<br />';
    }
}

It's printing acceptable every time even though https is contained within the $link variable.

Upvotes: 30

Views: 53349

Answers (5)

Aniket B
Aniket B

Reputation: 488

strpos

function may return Boolean FALSE, but may also return a non-Boolean value which evaluates to FALSE.

So I did like this

if (strpos($link, $unacceptable) !== false) {
    //Code
}

Upvotes: 1

Manish Trivedi
Manish Trivedi

Reputation: 3559

Strpos always return position like you search "httpsL" in your string('https://google.com';) then it return 0th position and PHP evaluate it as false.

please see this link:(Hope its very usefull for you): http://php.net/manual/en/function.strpos.php

Upvotes: 2

Foo Bah
Foo Bah

Reputation: 26251

Your failure condition is wrong.

strpos returns false if match is not found, so you need to explicitly check

if (strpos($link, $unacceptable) !== false) {

Upvotes: 8

acrosman
acrosman

Reputation: 12900

strpos() does not return true when it finds a match, it returns the position of the first matching string. Watchout, if the match is a the beginning of the string it will return an index of zero which will compare as equal to false unless you use the === operator.

Upvotes: 15

coreyward
coreyward

Reputation: 80041

When in doubt, read the docs:

[strpos] Returns the numeric position of the first occurrence of needle in the haystack string.

So you want to try something more like:

// ...
if (strpos($link, $unacceptable) !== false) {

Because otherwise strpos is returning a number, and you're looking for a boolean true.

Upvotes: 80

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