Code Hitung PPH21

pph21.php

<?php
echo "\n";
echo "Berapa pendapatan (gaji dan lainnya) Anda per bulan? ";
$handle = fopen ("php://stdin","r");
$gaji = fgets($handle);
echo "Berapa pengeluaran (asuransi, jamsostek, dll) Anda per bulan? ";
$handle = fopen ("php://stdin","r");
$pengurangan = fgets($handle) ? : 0;
echo "Berapa bonus dan THR Anda peroleh dalam setahun? ";
$handle = fopen ("php://stdin","r");
$thrbonus = fgets($handle) ? : 0;
echo "Anda sudah menikah (Y/T)? ";
$handle = fopen ("php://stdin","r");
$nikah = fgets($handle);
if(trim($nikah) === 'Y' || trim($nikah) === 'y'){
    $nikah = true;
} else {
    $nikah = false;
}
echo "Jumlah tanggungan? ";
$handle = fopen ("php://stdin","r");
$tanggungan = fgets($handle);

if ($nikah) {
    if ($tanggungan >= 3) {
        $ptkp = "30375000";
    } elseif ($tanggungan === 2) {
        $ptkp = "28350000";
    } elseif ($tanggungan === 1) {
        $ptkp = "26325000";
    } else {
        $ptkp = "24300000";
    }
} else { 
    if ($tanggungan >= 3) {
        $ptkp = "32400000";
    } elseif ($tanggungan === 2) {
        $ptkp = "30375000";
    } elseif ($tanggungan === 1) {
        $ptkp = "28350000";
    } else {
        $ptkp = "26325000";
    }
}

$gajiTahunan = (12 * ($gaji - $pengurangan)) + $thrbonus;
$biayaJabatan = 0.05 * $gajiTahunan;
$gajiKenaPajak = $gajiTahunan - $biayaJabatan - $ptkp;

$pajak = 0;
if ($gajiKenaPajak > 0) {
    if ($gajiKenaPajak > 500000000) {
        $tier1 = 0.05 * 50000000;
        $tier2 = 0.1 * 200000000;
        $tier3 = 0.25 * 250000000;
        $tier4 = 0.3 * ($gajiKenaPajak - 500000000);
        $pajak = $tier1 + $tier2 + $tier3 + $tier4;
    } elseif ($gajiKenaPajak > 250000000) {
        $tier1 = 0.05 * 50000000;
        $tier2 = 0.1 * 200000000;
        $tier3 = 0.25 * ($gajiKenaPajak - 250000000);
        $pajak = $tier1 + $tier2 + $tier3;
    } elseif ($gajiKenaPajak > 50000000) {
        $tier1 = 0.05 * 50000000;
        $tier2 = 0.1 * ($gajiKenaPajak - 50000000);
        $pajak = $tier1 + $tier2;
    } else {
        $tier1 = 0.05 * $gajiKenaPajak;
        $pajak = $tier1;
    }
}

echo "\n";
echo "==========================================\n";
echo "= Pajak per tahun : ".str_pad(number_format($pajak), 20, " ", STR_PAD_LEFT)." =\n";
echo "= Pajak per bulan : ".str_pad(number_format($pajak/12), 20, " ", STR_PAD_LEFT)." =\n";
echo "==========================================\n";
?>

Dibagian fopen ("php://stdin","r"); di isi apa ya gan ?