why is the following php code not working:
$string = "123";
$search = "123";
if(strpos($string,$search))
{
echo "found";
}else{
echo "not found";
}
as $search is in $string - shouldn't it be triggered as found?
7 Answers
This is mentioned in the Manual: strpos()
This function may return Boolean FALSE, but may also return a non-Boolean value which evaluates to FALSE, such as 0 or "". Please read the section on Booleans for more information. Use the === operator for testing the return value of this function.
In your case the string is found at the index 0 and in php 0 == false
The solution is to just use the strict comparator
echo strpos($string,$search) === false
? "not found"
: "found";
Another one
echo is_int(strpos($string,$search))
? "found"
: "not found";
Or something ... lets say interesting :D Just for illustration. I don't recommend this one.
echo strpos('_' . $string,$search) // we just shift the string 1 to the right
? "found"
: "not found";
Comments
This is happening because the search string is being found at position 0. Try
if(strpos($string,$search) !== FALSE)
instead of
if(strpos($string,$search))
6 Comments
KingCrunch
(1 != false) === true. In fact ($x != false) === ($x == true) === ((boolean) $x) for every $x. Thus both code snippets are identical.
Ozair Kafray
@KingCrunch: so would if(strpos($string,$search) !== FALSE) be correct?
user1301428
@OzairKafray it worked for me using
!== false, it doesn't if I use != falseOzair Kafray
@user1301428: This was to highlight the difference between ===/!== and ==/!=, different things would work in different situations. To be sure what to use one should read the documentation for a function carefully and then assess his/her situation.
user1301428
@OzairKafray if I understand it correctly, when the needle is found at the beginning of the haystack, then !== should always be used, but I might be wrong
|
strpos returns the first offset where $search was found - 0. 0 in turn evaluates to false. Therefore the if fails.
If $search was not found, strpos returns FALSE. First check the return value for !== FALSE, and then check the offset.
Thanks to everyone who pointed this out in the comments.
4 Comments
grossvogel
... which is why the standard practice is to check whether
strpos(...) === FALSE. See the big warning on the man page: php.net/manual/en/function.strpos.php
Evert
Correct explanation, but it's better to strictly check if itis' not false (!== false)
KingCrunch
strpos($string,$search)>=0 does not work as expected, because (false >= 0) === true.
Ryan
You are of course correct - you really should check
!== FALSE !From the manual:
This function may return Boolean FALSE, but may also return a non-Boolean value which evaluates to FALSE, such as 0 or "". Please read the section on Booleans for more information. Use the === operator for testing the return value of this function.
In your example, you should use
$string = "123";
$search = "123";
if ( false !== strpos( $string, $search ) ) {
echo "found";
} else {
echo "not found";
}
Comments
strpos returns the numeric position of the string you want to search for if it finds it. So in your case, you want to be doing this instead:
$search = "123";
$string = "123";
if (strpos($string,$search)===false) { echo "not found"; }
else { echo "found"; }
basically it returns a false if it doesn't find your string
Comments
You can use this:
<?php
$string = "123";
$find = "123";
$strpos = strpos($string, $find);
if($strpos || $strpos === (int)0) {
echo "Found it!";
} else {
echo "Not Found!";
}
?>
strstrinstead.