請教一個函數

請問一個函數
我PHP是菜鳥，判斷一變數$a中是否包含另外一個變數中$b的字元，用什麼方法可以實現，謝謝


------解決方案--------------------
strpos

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

// Note our use of ===. Simply == would not work as expected
// because the position of 'a ' was the 0th (first) character.
if ($pos === false) {
echo "The string '$findme ' was not found in the string '$mystring ' ";
} else {
echo "The string '$findme ' was found in the string '$mystring ' ";
echo " and exists at position $pos ";
}

// We can search for the character, ignoring anything before the offset
$newstring = 'abcdef abcdef ';
$pos = strpos($newstring, 'a ', 1); // $pos = 7, not 0
?>

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