Php/docs/function.bindec
bindec
(PHP 4, PHP 5, PHP 7)
bindec — Binary to decimal
Description
bindec
( string $binary_string
) : int|float
Returns the decimal equivalent of the binary number represented by
the binary_string argument.
bindec() converts a binary number to an int or, if needed for size reasons, float.
bindec() interprets all
binary_string values as unsigned
integers. This is because bindec() sees
the most significant bit as another order of magnitude
rather than as the sign bit.
Parameters
binary_string- The binary string to convert. Any invalid characters in
binary_stringare silently ignored. As of PHP 7.4.0 supplying any invalid characters is deprecated.
Warning The parameter must be a string. Using other data types will produce unexpected results.
Return Values
The decimal value of binary_string
Changelog
| Version | Description |
|---|---|
| 7.4.0 | Passing invalid characters will now generate a deprecation notice.
The result will still be computed as if the invalid characters did not exist. |
Examples
Example #1 bindec() example
<?phpecho bindec('110011') . "\n";echo bindec('000110011') . "\n";echo bindec('111');?>
The above example will output:
51 51 7
Example #2 bindec() interprets input as unsigned integers
<?php/* * The lesson from this example is in the output * rather than the PHP code itself. */$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 int 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
