Database Manual / Reference / Query Language / Expressions

$bitAnd (expression operator)（表达式运算符）

Definition定义

New in version 6.3.在版本6.3中新增。

$bitAnd
Returns the result of a bitwise and operation on an array of int or long values.返回对int或long值数组进行按位AND运算的结果。

Syntax语法

The $bitAnd operator has the following syntax:$bitAnd运算符具有以下语法：

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

Behavior行为

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.如果操作数同时包含整数和长值，MongoDB符号将扩展计算出的整数结果并返回长值。否则，如果操作数仅包含整数或长整型，MongoDB将返回具有相应值类型的结果。

Note

All numbers in mongosh are doubles, not integers. mongosh中的所有数字都是双精度的，而不是整数。To specify integers in mongosh, use the Int32() or the Long() constructor. 要在mongosh中指定整数，请使用Int32()或Long()构造函数。To learn more, see Int32 or Long.要了解更多信息，请参阅Int32或Long。

To learn how your MongoDB driver handles numeric values, refer to your driver's documentation.要了解MongoDB驱动程序如何处理数值，请参阅驱动程序的文档。

If any arguments in the array are of a different data type such as a string, double, or decimal, MongoDB returns an error.如果数组中的任何参数属于不同的数据类型，如字符串、double或decimal，MongoDB将返回错误。

If the argument is an empty array, the operation returns Int32(-1).如果参数是空数组，则操作返回Int32(-1)。

If any of the operands equate to null, the operation returns null.如果任何操作数等于null，则操作返回null。

Examples示例

The examples on this page use the switches collection, which contains the following documents:此页面上的示例使用switches集合，其中包含以下文档：

db.switches.insertMany( [
    { _id: 0, a: Int32(0), b: Int32(127) },
    { _id: 1, a: Int32(2), b: Int32(3) },
    { _id: 2, a: Int32(3), b: Int32(5) }
] )

Bitwise AND with Two Integers按位AND两个整数

The following aggregation uses the $bitAnd operator in the $project stage:以下聚合在$project阶段使用$bitAnd运算符：

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

The operation returns the following results:该操作返回以下结果：

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

Bitwise AND with a Long and Integer带长整型的按位AND

The following aggregation uses the $bitAnd operator in the $project stage:以下聚合在$project阶段使用$bitAnd运算符：

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

The operation returns the following results:该操作返回以下结果：

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

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