Using PHP is_bool() to Check Boolean Variables

In PHP programming, it is often necessary to verify whether a variable is a boolean. PHP provides the built‑in is_bool() function for this purpose.

The is_bool() function returns true if the supplied variable is of boolean type, otherwise it returns false.

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 checks each variable with is_bool() and prints whether the variable is a boolean.

Running the code produces the following output:

变量 $var1 是布尔值<br/>变量 $var2 是布尔值<br/>变量 $var3 不是布尔值<br/>变量 $var4 不是布尔值<br/>

From the results, $var1 and $var2 are identified as booleans, while $var3 and $var4 are not, demonstrating that is_bool() correctly distinguishes true boolean values from other types such as integers and strings.

In summary, the is_bool() function is a useful tool for quickly checking variable types in PHP, helping developers write more reliable and type‑safe code.