gmp_setbit
gmp_setbit
(PHP 4 >= 4.0.4, PHP 5, PHP 7)
gmp_setbit — Set bit
Description
void gmp_setbit ( GMP &$a , int $index [, bool $bit_on = true ] )
Sets bit index
in a
.
Parameters
-
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.
-
index
-
The index of the bit to set. Index 0 represents the least significant bit.
-
bit_on
-
True to set the bit (set it to 1/on); false to clear the bit (set it to 0/off).
Examples
Example #1 gmp_setbit() example - 0 index
<?php $a = gmp_init("2"); // echo gmp_strval($a), ' -> 0b', gmp_strval($a, 2), "\n"; gmp_setbit($a, 0); // 0b10 now becomes 0b11 echo gmp_strval($a), ' -> 0b', gmp_strval($a, 2), "\n"; ?>
The above example will output:
2 -> 0b10 3 -> 0b11
Example #2 gmp_setbit() example - 1 index
<?php $a = gmp_init("0xfd"); echo gmp_strval($a), ' -> 0b', gmp_strval($a, 2), "\n"; gmp_setbit($a, 1); // index starts at 0 echo gmp_strval($a), ' -> 0b', gmp_strval($a, 2), "\n"; ?>
The above example will output:
253 -> 0b11111101 255 -> 0b11111111
Example #3 gmp_setbit() example - clearing a bit
<?php $a = gmp_init("0xff"); echo gmp_strval($a), ' -> 0b', gmp_strval($a, 2), "\n"; gmp_setbit($a, 0, false); // clear bit at index 0 echo gmp_strval($a), ' -> 0b', gmp_strval($a, 2), "\n"; ?>
The above example will output:
255 -> 0b11111111 254 -> 0b11111110
Notes
Note:
Unlike most of the other GMP functions, gmp_setbit() must be called with a GMP resource that already exists (using gmp_init() for example). One will not be automatically created.
See Also
- gmp_clrbit() - Clear bit
- gmp_testbit() - Tests if a bit is set
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Licensed under the Creative Commons Attribution License v3.0 or later.
https://secure.php.net/manual/en/function.gmp-setbit.php