Using PHP's is_bool() Function to Check Boolean Variables

In PHP programming, checking whether a variable is a boolean is a common task, and the built‑in is_bool() function makes this straightforward. This article introduces the usage of is_bool() and provides practical code examples.

The is_bool() function returns true if the supplied variable is of boolean type, otherwise it returns false . Below is a sample script that defines four variables with different types and uses is_bool() to test 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>";
}
?>

Running the script 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 . In contrast, $var3 (an integer 1) and $var4 (the string "true") are not booleans, so is_bool() returns false for them.

In summary, the is_bool() function is a useful tool for quickly determining a variable's boolean status, which is essential for many programming scenarios where type checking ensures correct logic flow.