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How to use gettype() function to determine the type of variable in PHP?
How to use gettype() function to determine the type of variable in PHP?
gettype()函数是PHP中的一个内置函数，用于获取变量的类型；它可用于检查现有变量的类型。下面本篇文章就来给大家介绍一下gettype()函数，希望对大家有所帮助。【视频教程推荐：PHP教程】
基本语法
string gettype ( $var )
参数：gettype()函数接受单个参数$va，表示需要检查其类型的变量的名称。
返回值：此函数会返回字符串类型的值。返回字符串的可能值为：
● boolean：表示变量为布尔类型
● integer：表示变量为整数类型
● double ：表示变量为float类型（由于历史原因，如果为float类型，则返回“double”)。
● string：表示变量为string类型
● array：表示变量为数组类型
● object：表示变量为对象类型
● resource：表示变量为resource类型
● NULL：表示变量为NULL类型
● unknown type：未知类型
代码示例
下面我们通过代码示例来看看gettype()函数的使用。
示例1：
<?php $var1 = true; // 布尔值 $var2 = 3; // 整数值 $var3 = 5.6; // 浮点值 $var4 = "Abc3462"; // 字符串值 $var5 = array(1, 2, 3); // 数组值 $var6 = new stdClass; // 对象 $var7 = NULL; // null值 $var8 = tmpfile(); // resource值 echo gettype($var1)."<br>"; echo gettype($var2)."<br>"; echo gettype($var3)."<br>"; echo gettype($var4)."<br>"; echo gettype($var5)."<br>"; echo gettype($var6)."<br>"; echo gettype($var7)."<br>"; echo gettype($var8)."<br>"; ?>
输出：
boolean integer double string array object NULL resource
示例2：
<?php
header("content-type:text/html;charset=utf-8");
$var1 = "php";
$var2 = 10 % 7;
$var3 = pow(10, 2);
$var4 = pow(10, 0.5);
$var5 =pow(-2,-3.2);
$var6 = sqrt(4);
echo "变量\$var1=".$var1." ，类型为：".gettype($var1)."<br>";
echo "变量\$var2=".$var2." ，类型为：".gettype($var2)."<br>";
echo "变量\$var3=".$var3." ，类型为：".gettype($var3)."<br>";
echo "变量\$var4=".$var4." ，类型为：".gettype($var4)."<br>";
echo "变量\$var5=".$var5." ，类型为：".gettype($var5). "<br>";
echo "变量\$var6=".$var6." ，类型为：".gettype($var6);
?>输出：
变量$var1=php ，类型为：string 变量$var2=3 ，类型为：integer 变量$var3=100 ，类型为：integer 变量$var4=3.1622776601684 ，类型为：double 变量$var5=NAN ，类型为：double 变量$var6=2 ，类型为：double
说明：pow(x,y) 函数返回 x 的 y 次方，返回值是 Integer或Float类型；sqrt() 函数返回一个数的平方根，返回值为Float类型的。NAN（非数），是计算机科学中数值数据类型的一类值，表示未定义或不可表示的值。
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