php變數類型與轉換

echo &#39;<h3>2.变量类型与转换</h3>&#39;;
echo &#39;<hr color="green">&#39;;

//標量:單值變數,包括整數,浮點,字串,布林四種

$age = 30; //1整型 integer
$salary = 1234.56; //2.浮点 float
$name = 'peter'; //3 字符串
$isMarried = true;  //4. 布尔型,true真,false假

//標量輸出echo,print或var_dump()可查看型別與值

echo $name.'的年龄是:'.$age.',工资是:'.$salary.',是否已婚:'.$isMarried;
echo &#39;<br>&#39;;
print $name; print &#39;<br>&#39;;
var_dump($name);
echo &#39;<hr color="red">&#39;;

//複合型別: 多值變數,包含陣列與物件二種

$books = ['php','mysql','html','css','javascript']; //数组
$student = new stdClass(); //创建空对象$student
$student->name = '王二小';  //添加属性name
$student->course = 'php';  //添加属性course
$student->grade = 80;     //添加属性grade

//複合變數輸出: print_r()或var_dump()

echo &#39;<pre class="brush:php;toolbar:false">&#39;; //格式化输出结果
print_r($books);
print_r($student);
var_dump($books);
var_dump($student);
echo &#39;<hr color="red">&#39;;

//特殊類型:資源類型,null

$file = fopen('demo.php','r') or die('打开失败');
echo fread($file, filesize('demo.php'));
fclose($file);

$price = null;

#echo '$price is '.$price;

/**

 * 變數類型查詢,設定與檢測

## * 1.類型查詢:

 * gettype($var)

 * 2.類型偵測:

 * 2.1: is_integer(),

 * 2.2: is_float(),

 * 2.3: is_string(),

 * 2.4: is_bool( ),

 *       2.5: is_array(),

 *       2.6: is_object(),

 *       2.7: is_null(),

 *       2.8: is_resource(),

 *       2.9: is_numeric()...

## * 3.型別轉換:

 * 3.1: 強制轉換: (int)$val,( string)$val...

 * 3.2: 暫時轉換(值轉換型別):intval(),floatval(),strval(),val是value

# *  3.3:永久轉換:settype($var,型別標識符)

 * /

$price = 186.79;
echo gettype($price);  //float/double浮点型,float和double同义
echo &#39;<hr>&#39;;
echo (int)$price;  //强制转为integer,186
echo &#39;<hr>&#39;;
echo $price;  //查看原始数据,仍是浮点型,并无变化
echo &#39;<hr>&#39;;
echo gettype($price);  //原始类型仍为double,并未发生变化
echo &#39;<hr>&#39;;
echo intval($price);  //临时将值转为整型,输出:186
echo &#39;<hr>&#39;;
echo $price; //输出原值,仍为186.79,原值并未发生变化
echo &#39;<hr>&#39;;
settype($price,&#39;integer&#39;);  //永久转为integer,返回布尔值
echo $price;  //查看值:186
echo &#39;<hr>&#39;;
echo gettype($price);  //类型为integer
echo &#39;<hr>&#39;;
echo is_integer($price)? &#39;Integer&#39; : &#39;Double&#39;; //Integer整型
echo &#39;<hr>&#39;;
//is_numeric():判断是否是数字或数字型字符串
var_dump(is_numeric(100));
var_dump(is_numeric(&#39;200&#39;));
var_dump(is_numeric(&#39;200php&#39;));

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