gmp_setbit
PHP function
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(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)
Set bit
Description
gmp_setbit(GMP $num, int $index, bool $value = true): void
Sets bit index in num.
Parameters
numA
GMPobject.indexThe index of the bit to set. Index 0 represents the least significant bit.
valueTrue to set the bit (set it to 1/on); false to clear the bit (set it to 0/off).
Return Values
Void
Examples
gmp_setbit() example - 0 index
php
<?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:
output
2 -> 0b10
3 -> 0b11gmp_setbit() example - 1 index
php
<?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:
output
253 -> 0b11111101
255 -> 0b11111111gmp_setbit() example - clearing a bit
php
<?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:
output
255 -> 0b11111111
254 -> 0b11111110Notes
Note
Unlike most of the other GMP functions, gmp_setbit() must be called with a GMP object that already exists (using gmp_init() for example). One will not be automatically created.