if string not contains php code example

Example 1: php check if string contains word

$myString = 'Hello Bob how are you?';
if (strpos($myString, 'Bob') !== false) {
    echo "My string contains Bob";
}

Example 2: php string contains

$mystring = 'abc';
$findme   = 'a';
$pos = strpos($mystring, $findme);