PHP 判斷是否包含在某個字符串中

1.用strpos函數，查找字符首次出現的位置，如果不存在則會返回false
$str= 'abc';
$needle= 'e';
$pos = strpos($str, $needle);
2.用strstr函數查找字符在字符串中首次出現，並返回字符出現開始的位置至結束的字符串
$email = '[e-mail]';
$domain = strstr($email, '@');
3.用explode分割字符串，如果返回的數組長度大於一則表示存在
$str= 'abc';
$needle = 'E';//判斷是否包含a這個字符
$tmparray = explode($needle,$str);
4.用in_array檢查數組中是否存在某個值
// bool in_array ( mixed $needle , array $haystack [, bool $strict = FALSE ] )
//in_array()例子
$os=array("Mac","NT","Irix","Linux");
if(in_array("Irix",$os)){
 echo "Got Irix";
}
if(in_array("mac",$os)){
 echo "Got mac";
}
//第二個條件失敗，因為in_array()是區分大小寫的 所以只輸出Got Irix
//in_array() 嚴格類型檢查例子
$a = array('1.10', 12.4, 1.13);
if (in_array('12.4', $a, true)) {
 echo "'12.4' found with strict check\n";
}
if (in_array(1.13, $a, true)) {
 echo "1.13 found with strict check\n";
}
//程序會輸出1.13 found with strict check
//in_array()中數組作為needle
$a = array(array('p', 'h'), array('p', 'r'), 'o');
if (in_array(array('p', 'h'), $a)) {
 echo "'ph' was found\n";
}
if (in_array(array('f', 'i'), $a)) {
 echo "'fi' was found\n";
}
if (in_array('o', $a)) {
 echo "'o' was found\n";
}
//程序會輸出
//'ph' was found
//'o' was found