search tags in a php string with strpos

Question

this is an UTF-8 string

$string = '<h2> a none english char - utf-8 string </h2>';

I want to check <h2> tag exist in $string or not

I try:

if(strpos($string , '<h2>'))
or
if(strpos($string , '<h2>') == true )
or
if(strpos($string , '<h2>') === true)
or
if(mb_strpos($string , '<h2>' ))

but all of these condition retrun false. whats the wrong?

Answer 1

Your tests fail because your "needle" string occurs right at the start of your haystack, therefore strpos() will return 0, to indicate start-of-string.

if (0)          -> false
if (0 == true)  -> false
if (0 === true) -> false

You cannot use equality in this case, you must use inequality:

if (strpos(...) !== FALSE)

comment followup:

I fail to see how it could "no effect at all":

php > $string = '<h2> a none english char - utf-8 string </h2>';
php > var_dump(strpos($string, '<h2>'));
int(0)
php > var_dump(strpos($string, '<h2>') == true);
bool(false)
php > var_dump(strpos($string, '<h2>') === true);
bool(false)
php > var_dump(mb_strpos($string, '<h2>'));
int(0)
php > var_dump(mb_strpos($string, '<h2>') !== false);
bool(true)