Using PHP is_bool() to Determine Boolean Types

In PHP, the is_bool() function checks whether a variable is of boolean type, returning true if it is and false otherwise.

Syntax:

bool is_bool ( mixed $var )

Parameter: $var – the variable to be tested.

Return value: true if $var is boolean, false otherwise.

Example code:

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

// Check each variable
if (is_bool($var1)) {
    echo "变量var1是布尔类型";
} else {
    echo "变量var1不是布尔类型";
}
if (is_bool($var2)) {
    echo "变量var2是布尔类型";
} else {
    echo "变量var2不是布尔类型";
}
if (is_bool($var3)) {
    echo "变量var3是布尔类型";
} else {
    echo "变量var3不是布尔类型";
}
if (is_bool($var4)) {
    echo "变量var4是布尔类型";
} else {
    echo "变量var4不是布尔类型";
}
?>

The output will be:

变量var1是布尔类型
变量var2是布尔类型
变量var3不是布尔类型
变量var4不是布尔类型

The example demonstrates that literals true and false are recognized as booleans, while a string "true" and integer 1 are not, illustrating how is_bool() can be used for type validation in real‑world PHP applications.