The "hexdec()" function converts a hexadecimal number to a decimal number.

    hexdec(hex_number)

In the above syntax "hex_number" is the hexadecimal number to be converted to decimal number.

    <?php
    echo hexdec(a) . "\n";
    echo hexdec(f);
    ?>

    10
    15

In the above example the hexadecimal numbers "a", "f" are converted to decimal numbers "10", "15".