dechex
RETURNS a STRING containing a HEXADECIMAL representation of the given DECIMAL number argument.
<?php
str dechex ( int $number )
where,
$number = The decimal value to be converted to hexadecimal
?>
$number
The decimal value to convert to hexadecimal.
| MINIMUM DECIMAL VALUE |
MAXIMUM DECIMAL VALUE |
bit |
| -4294967294 |
+4294967295 |
32 |
| -9223372036854775806 |
+9223372036854775807 |
64 |
| ed48 |
| MAXIMUN DECIMAL VALUE |
MAXIMUM HEXADECIMAL VALUE |
bit |
| 4294967295 |
ffffffff |
32 |
| 9223372036854775807 |
7fffffffffffffff |
64 |
| ed48 |
For the minimum and maximum values to convert under each architecture, see above tables.
EXERCISE
<?php
$nbr01_32m = -4294967294;
$nbr01_32M = 4294967295;
$nbr01_64m = -9223372036854775806;
$nbr01_64M = 9223372036854775807;
$nbr01_l = -1;
$nbr01_e = 1498;
$dechex_32m = dechex($nbr01_32m);
$dechex_32M = dechex($nbr01_32M);
$dechex_64m = dechex($nbr01_64m);
$dechex_64M = dechex($nbr01_64M);
$dechex_l = dechex($nbr01_l);
$dechex_e = dechex($nbr01_e);
echo 'dechex( ' . $nbr01_32m . ' )=<br>= ' .
$dechex_32m . '<br><br>';
echo 'dechex( ' . $nbr01_32M . ' )=<br>= ' .
$dechex_32M . '<br><br>';
echo 'dechex( ' . $nbr01_64m . ' )=<br>= ' .
$dechex_64m . '<br><br>';
echo 'dechex( ' . $nbr01_64M . ' )=<br>= ' .
$dechex_64M . '<br><br><br>';
echo 'dechex( ' . $nbr01_l . ' )=<br>= ' .
$dechex_l . '<br><br>';
echo 'dechex( ' . $nbr01_e . ' )=<br>= ' .
$dechex_e . '<br><br>';
?>
RESULT
dechex( -4294967294 )=
= ffffffff00000002
dechex( 4294967295 )=
= ffffffff
dechex( -9223372036854775806 )=
= 8000000000000002
dechex( 9223372036854775807 )=
= 7fffffffffffffff
dechex( -1 )=
= ffffffffffffffff
dechex( 1498 )=
= 5da
You must be careful when using this function, especially when handling negative values.
EXERCISE
<?php
$nbr02a = -61.3245;
$nbr02b = 61.3245;
$dehexa = dechex($nbr02a);
$dehexb = dechex($nbr02b);
echo 'FLOAT values:<br><br>';
echo 'dechex( ' . $nbr02a . ' ) = ' . $dehexa . '<br><br>';
echo 'dechex( ' . $nbr02b . ' ) = ' . $dehexb . '<br><br><br>';
echo 'This is the same as INTEGER values:<br><br>';
$nbr02c = -61;
$nbr02d = 61;
$dehexc = dechex($nbr02a);
$dehexd = dechex($nbr02b);
echo 'dechex( ' . $nbr02c . ' ) = ' . $dehexc . '<br><br>';
echo 'dechex( ' . $nbr02d . ' ) = ' . $dehexd . '<br><br>';
?>
RESULT
FLOAT values
dechex( -61.3245 ) = ffffffffffffffc3
dechex( 61.3245 ) = 3d
INTEGER values
dechex( -61 ) = ffffffffffffffc3
dechex( 61 ) = 3d
It does not matter if the value entered is of type FLOAT, because the treatment given by this function will always be of an INTEGER.
EXERCISE
<?php
if(PHP_VERSION < 8)
{
$nbr01_L = 9.199999E+19;
$dechex_L = dechex($nbr01_L);
echo 'dechex( ' . $nbr01_L . ' )= ' .
$dechex_L . '<br><br>';
}
else
{
echo 'This FLOAT value is supported by this PHP.<br><br>';
$nbr01_L = 9.199999E+18;
$dechex_L = dechex($nbr01_L);
echo 'dechex( ' . $nbr01_L . ' )= ' .
$dechex_L . '<br><br>';
}
?>
EXERCISE
<?php
$values = array(10,
3950.5,
3.9505e3,
03,
0x5F,
"10",
"3950.5",
"3.9505e3",
"039",
"0x5F",
true,
false,
null,
);
foreach ($values as $value) {
try {
echo $value . ' = ';
echo '( '. dechex($value) . ')<sub>16</sub>';
echo '<br><br>';
} catch (TypeError $exception) {
echo $exception->getMessage() . "<br><br>";
}
}
?>
EXERCISE
<?php
if (PHP_INT_SIZE != 8)
die("skip this test is for 64bit platform only");
define("MAX_64Bit", 9223372036854775807);
define("MAX_32Bit", 2147483647);
define("MIN_64Bit", -9223372036854775807 - 1);
define("MIN_32Bit", -2147483647 - 1);
$longVals = array(
MAX_64Bit, MIN_64Bit, MAX_32Bit, MIN_32Bit,
MAX_64Bit - MAX_32Bit, MIN_64Bit - MIN_32Bit,
MAX_32Bit + 1, MIN_32Bit - 1, MAX_32Bit * 2,
(MAX_32Bit * 2) + 1, (MAX_32Bit * 2) - 1,
MAX_64Bit -1, MAX_64Bit + 1,
MIN_64Bit + 1, MIN_64Bit - 1
);
foreach ($longVals as $longVal) {
echo "Testing: $longVal<br>";
try {
var_dump(dechex($longVal));
echo '<br><br>';
} catch (TypeError $exception) {
echo $exception->getMessage() . "<br><br>";
}
}
?>
EXERCISE
<?php
/*
if (PHP_INT_SIZE != 4)
die("skip this test is for 32bit platform only");
*/
echo "Testing dechex() : usage variations<br>";
//get an unset variable
$unset_var = 10;
unset ($unset_var);
// heredoc string
$heredoc = <<<EOT
abc
xyz
EOT;
// get a class
class classA
{
}
// get a resource variable
$fp = fopen(__FILE__, "r");
$inputs = array(
// int data
/*1*/ 0,
1,
12345,
-2345,
4294967295, // largest decimal
4294967296,
// float data
/*7*/ 10.5,
-10.5,
12.3456789000e10,
12.3456789000E-10,
.5,
// null data
/*12*/ NULL,
null,
// boolean data
/*14*/ true,
false,
TRUE,
FALSE,
// empty data
/*18*/ "",
'',
array(),
// string data
/*21*/ "abcxyz",
'abcxyz',
$heredoc,
// object data
/*24*/ new classA(),
// undefined data
/*25*/ @$undefined_var,
// unset data
/*26*/ @$unset_var,
// resource variable
/*27*/ $fp
);
// loop through each element of $inputs
// to check the behaviour of dechex()
foreach($inputs as $i => $input) {
$iterator = $i + 1;
echo "<br>Iteration: $iterator<br>";
try {
var_dump(dechex($input));
echo '<br><br>';
} catch (TypeError $exception) {
echo $exception->getMessage() . "<br><br>";
}
$iterator++;
}
fclose($fp);
?>
EXERCISE
<?php
if (PHP_INT_SIZE != 8)
die("skip this test is for 64bit platform only");
echo "Testing dechex() : usage variations<br>";
//get an unset variable
$unset_var = 10;
unset ($unset_var);
// heredoc string
$heredoc = <<<EOT
abc
xyz
EOT;
// get a class
class classA
{
}
// get a resource variable
$fp = fopen(__FILE__, "r");
$inputs = array(
// int data
/*1*/ 0,
1,
12345,
-2345,
18446744073709551615,
// largest decimal
18446744073709551616,
// float data
/*7*/ 10.5,
-10.5,
12.3456789000e10,
12.3456789000E-10,
.5,
// null data
/*12*/ NULL,
null,
// boolean data
/*14*/ true,
false,
TRUE,
FALSE,
// empty data
/*18*/ "",
'',
array(),
// string data
/*21*/ "abcxyz",
'abcxyz',
$heredoc,
// object data
/*24*/ new classA(),
// undefined data
/*25*/ @$undefined_var,
// unset data
/*26*/ @$unset_var,
// resource variable
/*27*/ $fp
);
// loop through each element of $inputs
// to check the behaviour of dechex()
foreach($inputs as $i => $input) {
$iterator = $i + 1;
echo "<br>Iteration: $iterator<br><br>";
try {
var_dump(dechex($input));
echo '<br>';
} catch (TypeError $exception) {
echo $exception->getMessage() . "<br><br>";
}
}
fclose($fp);
?>