Int64 编辑

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Because JavaScript doesn't currently include standard support for 64-bit integer values, js-ctypes offers the Int64 and UInt64 objects to let you work with C functions and data that need (or may need) values represented using a 64-bit data type.

You use the Int64 object to create and manipulate 64-bit signed integers.

Note: It's important to note that the 64-bit integer objects created by Int64 are not Int64 objects; rather, they're opaque objects whose values you manipulate through the other methods on the Int64 object. See 64-bit integers for details.

Syntax

Creates and returns a new 64-bit signed integer.

Int64 Int64(
  value
);

Parameters

value

The value to assign the new 64-bit integer object. This may be specified as an integer (if the value can be represented as a 32-bit value), another 64-bit integer object (either signed or unsigned), or as a string, which may consist of an optional minus sign, followed by either a decimal number or "0x" or "0X" followed by a hexadecimal number. The string is then converted into the corresponding 64-bit integer value. You can therefore use a string to represent a 64-bit value that is too large to represent as a 32-bit JavaScript Number.

Return value

A new object representing the specified value.

Exceptions thrown

TypeError

The specified value cannot be converted into a 64-bit integer. Either it's not a Number, String, or 64-bit integer object, or it's a string that is incorrectly formatted or contains a value outside the range that can be represented in 64 bits. This will also be thrown if the source value is a floating-point number that can't be precisely represented as a 64-bit integer.

Method overview

Number compare(a, b);

Number hi(a);

Int64 join(high, low);

Number lo(a);

String toSource();

String toString([radix]);

Methods

compare()

Compares two 64-bit integer values.

Number compare(
  a,
  b
);

Parameters

a

The first value to compare.

b

The second value to compare.

Return value

The returned value is:

-1 if a < b,
  0 if a == b, and
  1 if a > b.

Exceptions thrown

TypeError

One or both of the specified values is not a 64-bit integer (either signed or unsigned).

hi()

Returns the high 32 bits of the specified value.

Number hi(
  num
);

Parameters

num

The value whose high 32 bits are to be returned.

Return value

The high 32 bits of num are returned. This is essentially num >> 32.

Exceptions thrown

TypeError

num is not a 64-bit integer object.

lo()

Returns the low 32 bits of the specified value.

Number lo(
  num
);

Parameters

num

The Int64 value whose low 32 bits are to be returned.

Return value

The low 32 bits of num are returned. This is essentially num & 0xFFFFFFFF.

Exceptions thrown

TypeError

num is not a 64-bit integer object.

join()

Creates a 64-bit integer object whose value is constructed using the specified high and low order 32-bit values.

Int64 join(
  high,
  low
);

Parameters

high

The high-order 32 bits of the value to create.

low

The low-order 32 bits of the value to create.

Return value

A new 64-bit integer object comprised of the two values merged together. The returned value is (high << 32) + low.

Exceptions thrown

TypeError

One or both of the specified numbers is not a JavaScript number with an integral value.

toSource()

This method is for internal debugging use only.

Warning: Do not rely on the value returned by this method, as it's subject to change at any time, depending on the debugging needs of the developers.

toString()

Returns a string representation of the object's numeric value.

String toString(
  [radix]
);

Parameters

radix Optional

The radix (base) to use when constructing the string. If you don't specify a radix, base 10 is used.

Return value

A string representation of the value in the specified radix. This string consists of a leading minus sign, if the value was negative, followed by one or more lower-case digits in the specified radix.

See Also

• ctypes
• UInt64