PHP--笔试题

1、比较大小

var_dump(10 == "10a1"); //10 ==10 truevar_dump("10" == "10a1"); //falsevar_dump("10" == "1e1"); //10 ==10 truevar_dump(null == 0); //0 == 0 truevar_dump(true == 0); //falsevar_dump(true == 1); //true

运算数1类型 运算数2类型 结果 string或null 任何其他类型 将null转换为”“,进行数字或词汇比较 bool或null 任何其他类型 转换为bool, false string,resource或number string,resource,或number 将字符串和资源转换为数字，按数字比较 array array 具有较少成员的数组较小，如果count相同，并且运算数1中的键不存在与运算数2中则数组无法比较，否则按个比较 object 任何其他类型 object总是最大 array 任何其他类型 array总是最大

2、$str="hello world test"，用一行代码分割字符串，并分别赋给三个变量，两种方法

list($a,$b,$c) = explode(' ', $str)
list($a, $b, $c) = preg_split("/\s+/", $str)

3、php连接mysql及查询操作

/*原始mysql扩展在php5.5之后不支持使用，mysql扩展是针对mysql4.1.3设计的,mysql4.1.3之后版本推荐使用mysqli*///连接到数据库//方法1$mysqli = mysqli_connenct($server_name,$username,$password, $database, $port);if (mysqli_connect_errno($mysqli)) {   echo "Failed to connect MySQL:" . mysqli_connect_error();}//方法2:面向对象方法$msyqli = new mysqli("localhost", "user", "password", "database", 3306);if($mysqli->connect_errno) {   echo "Failed to connect MySQL:" . $mysqli->connnect_errno . $mysqli->connect_error;}//从user取出数据$res = $mysqli->query("SELECT * FROM user order by id desc limit 2");$data = $res->fatch_all(MYSQLI_ASSOC);//stmt查询$sql1 = "select * from user where id<?";$stmt1 = $mysqli->prepare($sql1);$stmt1->bind_param('i', $i);$i = 5;$stmt1->execute();$result = $stmt1->get_result();$data = $result->fetch_all(MYSQLI_ASSOC);var_dump($data);$stmt1->close();//遍历user的id$res = $mysqli->query("SELECT * FROM user");//移动记录指针$res = data_seek(0);while ($row = $res->fetch_assoc()) {      echo "uid = " . $row['uid] . "\n";}