Using PHP is_bool() to Check Boolean Variables

In PHP programming, the built‑in is_bool() function is used to determine whether a variable holds a boolean value.

The function returns true if the argument is of type boolean and false otherwise, making it a simple boolean‑type checker.

Below is a complete example that defines four variables with different types and applies is_bool() to each:

<?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 outputs which variables are booleans and which are not, producing:

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 result we see that $var1 and $var2 are true booleans, while $var3 (an integer) and $var4 (a string) are not, illustrating how is_bool() distinguishes actual boolean types from other values.

In summary, is_bool() is a useful function for quickly checking variable types, and mastering its use can make PHP code more reliable and easier to debug.