get substring contain spacific charactor in php code example

Example 1: How do I check if a string contains a specific word?

$a = 'Hello world?';

if (strpos($a, 'Hello') !== false) { //PAY ATTENTION TO !==, not !=
    echo 'true';
}
if (stripos($a, 'HELLO') !== false) { //Case insensitive
    echo 'true';
}

Example 2: php check if string contains a char

$haystack = 'This is my haystack that we shall check'
$has_A = strpos($haystack, 'A') !== false;
$has_a = strpos($haystack, 'a') !== false;