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

In PHP programming, checking whether a variable holds a boolean value is a common task, and the language provides the built‑in is_bool() function for this purpose.

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

Below is a complete example 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 this script produces the following output, indicating which variables are recognized as booleans:

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

The result shows that $var1 and $var2 are boolean values because they were assigned the literals true and false . In contrast, $var3 holds an integer (1) and $var4 holds a string ("true"), so is_bool() correctly reports them as non‑boolean.

In summary, the is_bool() function is a simple yet powerful tool for quickly determining a variable’s boolean status, which is essential for reliable type checking in PHP applications.