# Method `&()

- Method
**`&**

`mixed`

**`&(**`mixed`

`arg1`

**)**

`mixed`

**`&(**`mixed`

`arg1`

,`mixed`

`arg2`

,`mixed`

...`extras`

**)**

`mixed`

**`&(**`object`

`arg1`

,`mixed`

`arg2`

**)**

`mixed`

**`&(**`mixed`

`arg1`

,`object`

`arg2`

**)**

`int`

**`&(**`int`

`arg1`

,`int`

`arg2`

**)**

`string`

**`&(**`string`

`arg1`

,`string`

`arg2`

**)**

`array`

**`&(**`array`

`arg1`

,`array`

`arg2`

**)**

`mapping`

**`&(**`mapping`

`arg1`

,`mapping`

`arg2`

**)**

`mapping`

**`&(**`mapping`

`arg1`

,`array`

`arg2`

**)**

`mapping`

**`&(**`mapping`

`arg1`

,`multiset`

`arg2`

**)**

`multiset`

**`&(**`multiset`

`arg1`

,`multiset`

`arg2`

**)**

`type`

**`&(**`type`

|`program`

`arg1`

,`type`

|`program`

`arg2`

**)**- Description
Bitwise and/intersection.

Every expression with the

`&`

operator becomes a call to this function, i.e.`a&b`

is the same as`predef::`&(a,b)`

.- Returns
If there's a single argument, that argument is returned.

If there are more than two arguments the result is:

``&(`&(`

,`arg1`

`arg2), @`

`extras).`

Otherwise, if

`arg1`

is an object with an lfun::`&(), that function is called with`arg2`

as argument, and its result is returned.Otherwise, if

`arg2`

is an object with an lfun::``&(), that function is called with`arg1`

as argument, and its result is returned.Otherwise the result depends on the argument types:

`arg1`

can have any of the following types:`int`

Bitwise and of

`arg1`

and`arg2`

.`string`

The result is a string where each character is the bitwise and of the characters in the same position in

`arg1`

and`arg2`

. The arguments must be strings of the same length.`array`

|`mapping`

|`multiset`

The result is like

`arg1`

but only with the elements/indices that match any in`arg2`

(according to `>, `<, `== and, in the case of mappings, hash_value).`type`

|`program`

Type intersection of

`arg1`

and`arg2`

.The function is not destructive on the arguments - the result is always a new instance.

- Note
If this operator is used with arrays or multisets containing objects which implement lfun::`==() but

**not**lfun::`>() and lfun::`<(), the result will be undefined.- See also