bindec

Binary to decimal

&reftitle.description; ``int``float```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 `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.

&reftitle.parameters;

`binary_string`

- The binary string to convert. Any invalid characters in `binary_string` are silently ignored. As of PHP 7.4.0 supplying any invalid characters is deprecated.

The parameter must be a string. Using other data types will produce unexpected results.

&reftitle.returnvalues;

The decimal value of `binary_string`

&reftitle.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.

&reftitle.examples;

### `bindec` example

    <?php
    echo bindec('110011') . "\n";
    echo bindec('000110011') . "\n";

    echo bindec('111');
    ?>

&example.outputs;

    51
    51
    7

### `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";
    }
    ?>

&example.outputs.32bit;

    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

&example.outputs.64bit;

    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

&reftitle.notes;

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.

&reftitle.seealso;

- `decbin`
- `octdec`
- `hexdec`
- `base_convert`