ZEND PHP 5 Certification STUDY GUIDE

80 ” Strings And Patterns
You can also specify an optional third parameter to strpos() to indicate that you
want the search to start from a specific position within the haystack. For example:
$haystack = ’123456123456’;
$needle = ’123’;
echo strpos ($haystack, $needle); // outputs 0
echo strpos ($haystack, $needle, 1); // outputs 6
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The strstr() function works similarly to strpos() in that it searches the haystack
for a needle. The only real difference is that this function returns the portion of the
haystack that starts with the needle instead of the latter’s position:
$haystack = ’123456’;
$needle = ’34’;
echo strstr ($haystack, $needle); // outputs 3456
In general, strstr() is slower than strpos()—therefore, you should use the latter if
your only goal is to determine whether a certain needle occurs inside the haystack.
Also, note that you cannot force strstr() to start looking for the needle from a given
location by passing a third parameter.
Both strpos() and strstr() are case sensitive and start looking for the needle from
the beginning of the haystack. However, PHP provides variants that work in a caseinsensitive
way or start looking for the needle from the end of the haystack. For
example:
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// Case-insensitive search
echo stripos(’Hello World’, ’hello’); // outputs zero
echo stristr(’Hello My World’, ’my’); // outputs "My World"
// Reverse search
echo strrpos (’123123’, ’123’); // outputs 3