DecToHex.php

<?php
    const MAX_INT = 2 ** 32 - 1;
    echo("Input an unsigned integer number\r\n");
    $uNum = intval(chop(fgets(STDIN)));
    if(($uNum < 0) or ($uNum > MAX_INT))
    {
        echo("Invalid number format");
        exit(0);
    }
    echo("Lower case ? (y/n) ");
    $chAnswer = fgetc(STDIN);
    $bLowerCase = (($chAnswer == "y") or ($chAnswer == "Y"));
    $uTempVal = $uNum;
    $strHexNum = "";
    while ($uTempVal > 0)
    {
        $chHexDigit = '\0';
        $nHexDigit = $uTempVal % 16;
        if($nHexDigit >= 0 && $nHexDigit <= 9)
            $chHexDigit = chr($nHexDigit + ord("0"));
        else if($nHexDigit >= 10 && $nHexDigit <= 15 && $bLowerCase)
            $chHexDigit = chr($nHexDigit - 10 + ord("a"));
        else if($nHexDigit >= 10 && $nHexDigit <= 15)
            $chHexDigit = chr($nHexDigit - 10 + ord("A"));
        $strHexNum = $chHexDigit . $strHexNum;
        $uTempVal = intdiv($uTempVal, 16);
    }
    if(strlen($strHexNum) == 0)
    {
        $strHexNum = "0";
    }
    printf("The hexadecimal equivalent of the decimal number %d is %s\r\n", $uNum, $strHexNum);
    fgetc(STDIN);
?>