php man page for gmp_setbit

GMP_SETBIT(3)								 1							     GMP_SETBIT(3)

gmp_setbit - Set bit

SYNOPSIS
       void gmp_setbit (GMP  &$a, int  $index, [bool  $bit_on = true])

DESCRIPTION
	Sets bit $index in $a.

PARAMETERS
	      o $a
		- The value to modify. Either a GMP number resource in PHP 5.5 and earlier, a GMP object in PHP 5.6 and later, or a numeric string
		provided that it is possible to convert the latter to a number.

	      o $index
		- The index of the bit to set. Index 0 represents the least significant bit.

	      o $bit_on
		- True to set the bit (set it to 1/on); false to clear the bit (set it to 0/off).

RETURN VALUES
	A GMP number resource in PHP 5.5 and earlier, or a GMP object in PHP 5.6 and later.

EXAMPLES
       Example #1

	      gmp_setbit(3) example - 0 index

	      <?php
	      $a = gmp_init("2"); //
	      echo gmp_strval($a), ' -> 0b', gmp_strval($a, 2), "
";
	      gmp_setbit($a, 0); // 0b10 now becomes 0b11
	      echo gmp_strval($a), ' -> 0b', gmp_strval($a, 2), "
";
	      ?>

	      The above example will output:

	      2 -> 0b10
	      3 -> 0b11

       Example #2

	      gmp_setbit(3) example - 1 index

	      <?php
	      $a = gmp_init("0xfd");
	      echo gmp_strval($a), ' -> 0b', gmp_strval($a, 2), "
";
	      gmp_setbit($a, 1); // index starts at 0
	      echo gmp_strval($a), ' -> 0b', gmp_strval($a, 2), "
";
	      ?>

	      The above example will output:

	      253 -> 0b11111101
	      255 -> 0b11111111

       Example #3

	      gmp_setbit(3) example - clearing a bit

	      <?php
	      $a = gmp_init("0xff");
	      echo gmp_strval($a), ' -> 0b', gmp_strval($a, 2), "
";
	      gmp_setbit($a, 0, false); // clear bit at index 0
	      echo gmp_strval($a), ' -> 0b', gmp_strval($a, 2), "
";
	      ?>

	      The above example will output:

	      255 -> 0b11111111
	      254 -> 0b11111110

NOTES
       Note

	       Unlike most of the other GMP functions, gmp_setbit(3) must be called with a GMP resource that already exists (using gmp_init(3) for
	      example). One will not be automatically created.

SEE ALSO
       gmp_clrbit(3), gmp_testbit(3).

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