Using PHP is_bool() to Check Whether a Variable Is Boolean

In PHP programming we often need to verify if a variable is a boolean. PHP provides the built-in function is_bool() for this purpose.

The is_bool() function returns true when the supplied variable is of boolean type and false otherwise.

Below is a practical example that defines four variables with different types and uses is_bool() to check each one:

<?php
$var1 = true;
$var2 = false;
$var3 = 1;
$var4 = "true";

if (is_bool($var1)) {
    echo "变量 $var1 是布尔值<br>";
} else {
    echo "变量 $var1 不是布尔值<br>";
}

if (is_bool($var2)) {
    echo "变量 $var2 是布尔值<br>";
} else {
    echo "变量 $var2 不是布尔值<br>";
}

if (is_bool($var3)) {
    echo "变量 $var3 是布尔值<br>";
} else {
    echo "变量 $var3 不是布尔值<br>";
}

if (is_bool($var4)) {
    echo "变量 $var4 是布尔值<br>";
} else {
    echo "变量 $var4 不是布尔值<br>";
}
?>

The script creates $var1 (boolean true), $var2 (boolean false), $var3 (integer 1), and $var4 (string "true"). It then applies is_bool() to each variable and prints a message indicating whether the variable is a boolean.

Running the code produces the following output:

变量 $var1 是布尔值
变量 $var2 是布尔值
变量 $var3 不是布尔值
变量 $var4 不是布尔值

From the results we see that $var1 and $var2 are recognized as booleans because they were assigned the literal values true and false . $var3 (integer 1) and $var4 (string "true") are not booleans, so is_bool() returns false for them.

In summary, the is_bool() function is a handy tool for quickly determining a variable's boolean status, which is a common requirement in robust PHP applications.