php man page for bindec

BINDEC(3)								 1								 BINDEC(3)

bindec - Binary to decimal

SYNOPSIS
       number bindec (string  $binary_string)

DESCRIPTION
	Returns the decimal equivalent of the binary number represented by the $binary_string argument.

       bindec(3) converts a binary number to an integer or, if needed for size reasons, float.

       bindec(3)  interprets  all  $binary_string  values as unsigned integers. This is because bindec(3) sees the most significant bit as another
       order of magnitude rather than as the sign bit.

PARAMETERS
	      o $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(3) example

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

	      echo bindec('111');
	      ?>

	      The above example will output:

	      51
	      51
	      7

       Example #2

	      bindec(3) 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
";

		  $format = '%0' . (PHP_INT_SIZE * 8) . 'b';
		  $bin = sprintf($format, $input);
		  echo "binary:       $bin
";

		  ini_set('precision', 20);  // For readability on 64 bit boxes.
		  $dec = bindec($bin);
		  echo 'bindec():     ' . $dec . "
";

		  if ($note) {
		      echo "NOTE:	  $note
";
		  }

		  echo "
";
	      }
	      ?>

	      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(3), octdec(3), hexdec(3), base_convert(3).

PHP Documentation Group 														 BINDEC(3)