# gmp_setbit

(PHP 4 >= 4.0.4, PHP 5)

gmp_setbit — Set bit

### Description

void gmp_setbit ( resource `&$a` , int `$index` [, bool `$set_clear` ] )

Sets bit `index` in `a` .

### Parameters

`a`

  The number being set to.

  It can be either a GMP number resource, or a numeric string given that it is possible to convert the latter to a number.

`index`

  The set bit.

`set_clear`

  Defines if the bit is set to 0 or 1. By default the bit is set to 1. Index starts at 0.

### Return Values

A GMP number resource.

### Examples

Example#1 gmp_setbit() example

`<?php
$a = gmp_init("0xfd");
gmp_setbit($a, 1); // index starts at 0
echo gmp_strval($a) . "\n";
?>`

The above example will output:

    255

### 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()
- gmp_testbit()