$bitAnd (aggregation)

Definition

$bitAnd

Returns the result of a bitwise and operation on an array of int or long values.

Syntax

The $bitAnd operator has the following syntax:

{ $bitAnd: { [ <expression1>, <expression2>, ... ] }

Behavior

If the operands include both integers and long values, MongoDB sign-extends the calculated integer result and returns a long value. Otherwise, if the operands include only integers or only longs, MongoDB returns results with the corresponding value type.

If any arguments in the array are of a different data type such as a string, double, or decimal, MongoDB returns an error.

If the argument is an empty array, the operation returns NumberInt(-1).

If any of the operands equate to null, the operation returns null.

Examples

The examples on this page use the switches collection, which contains the following documents:

db.switches.insertMany( [
    { _id: 0, a: NumberInt(0), b: NumberInt(127) },
    { _id: 1, a: NumberInt(2), b: NumberInt(3) },
    { _id: 2, a: NumberInt(3), b: NumberInt(5) }
] )

db.switches.aggregate( [
  {
    $project: {
      result: {
        $bitAnd: [ "$a", "$b" ]
      }
    }
  }
])

  [
    { _id: 0, result: 0 }
    { _id: 1, result: 2 }
    { _id: 2, result: 1 }
  ]

db.switches.aggregate( [
  {
    $project: {
      result: {
        $bitAnd: [ "$a", NumberLong("63") ]
      }
    }
  }
])

  [
    { _id: 0, result: NumberLong("0") }
    { _id: 1, result: NumberLong("2") }
    { _id: 2, result: NumberLong("3") }
  ]

Learn More

• Aggregation Operators

• $bit