bindec
bindec
(PHP 4, PHP 5, PHP 7)
bindec — Binary to decimal
Description
number bindec ( string $binary_string )
Returns the decimal equivalent of the binary number represented by the binary_string argument.
bindec() converts a binary number to an integer or, if needed for size reasons, float.
bindec() interprets all binary_string values as unsigned integers. This is because bindec() sees the most significant bit as another order of magnitude rather than as the sign bit.
Parameters
binary_string
The binary string to convert
Warning
The parameter must be a string. Using other data types will produce unexpected results.
Return Values
The decimal value of binary_string
Examples
Example #1 bindec() example
<?php
echo bindec('110011') . "\n";
echo bindec('000110011') . "\n";
echo bindec('111'
?>
The above example will output:
51
51
7
Example #2 bindec() interprets input as unsigned integers
<?php
/*
* The lesson from this example is in the output
* rather than the PHP code itself.
*/
$magnitude_lower = pow(2, (PHP_INT_SIZE * 8) - 2
p($magnitude_lower - 1
p($magnitude_lower, 'See the rollover? Watch it next time around...'
p(PHP_INT_MAX, 'PHP_INT_MAX'
p(~PHP_INT_MAX, 'interpreted to be one more than PHP_INT_MAX'
if (PHP_INT_SIZE == 4) {
$note = 'interpreted to be the largest unsigned integer';
} else {
$note = 'interpreted to be the largest unsigned integer
(18446744073709551615) but skewed by float precision';
}
p(-1, $note
function p($input, $note = '') {
echo "input: $input\n";
$format = '%0' . (PHP_INT_SIZE * 8) . 'b';
$bin = sprintf($format, $input
echo "binary: $bin\n";
ini_set('precision', 20 // For readability on 64 bit boxes.
$dec = bindec($bin
echo 'bindec(): ' . $dec . "\n";
if ($note) {
echo "NOTE: $note\n";
}
echo "\n";
}
?>
Output of the above example on 32 bit machines:
input: 1073741823
binary: 00111111111111111111111111111111
bindec(): 1073741823
input: 1073741824
binary: 01000000000000000000000000000000
bindec(): 1073741824
NOTE: See the rollover? Watch it next time around...
input: 2147483647
binary: 01111111111111111111111111111111
bindec(): 2147483647
NOTE: PHP_INT_MAX
input: -2147483648
binary: 10000000000000000000000000000000
bindec(): 2147483648
NOTE: interpreted to be one more than PHP_INT_MAX
input: -1
binary: 11111111111111111111111111111111
bindec(): 4294967295
NOTE: interpreted to be the largest unsigned integer
Output of the above example on 64 bit machines:
input: 4611686018427387903
binary: 0011111111111111111111111111111111111111111111111111111111111111
bindec(): 4611686018427387903
input: 4611686018427387904
binary: 0100000000000000000000000000000000000000000000000000000000000000
bindec(): 4611686018427387904
NOTE: See the rollover? Watch it next time around...
input: 9223372036854775807
binary: 0111111111111111111111111111111111111111111111111111111111111111
bindec(): 9223372036854775807
NOTE: PHP_INT_MAX
input: -9223372036854775808
binary: 1000000000000000000000000000000000000000000000000000000000000000
bindec(): 9223372036854775808
NOTE: interpreted to be one more than PHP_INT_MAX
input: -1
binary: 1111111111111111111111111111111111111111111111111111111111111111
bindec(): 18446744073709551616
NOTE: interpreted to be the largest unsigned integer
(18446744073709551615) but skewed by float precision
Notes
Note: The function can convert numbers that are too large to fit into the platforms integer type, larger values are returned as float in that case.
See Also
- decbin() - Decimal to binary
- octdec() - Octal to decimal
- hexdec() - Hexadecimal to decimal
- base_convert() - Convert a number between arbitrary bases
← base_convert
ceil →
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Licensed under the Creative Commons Attribution License v3.0 or later.
