# uint64

64-bit unsigned integer arrays

## Description

Variables in MATLAB® of data type (class) uint64 are stored as 8-byte (64-bit) unsigned integers. For example:

y = uint64(10);
whos y
Name      Size            Bytes  Class     Attributes

y         1x1                 8  uint64

## Creation

Some array creation functions allow you to specify the data type. For instance, zeros(100,'uint64') creates a 100-by-100 matrix of zeros of type uint64.

If you have an array of a different type, such as double or single, then you can convert that array to an array of type uint64 by using the uint64 function.

### Description

example

Y = uint64(X) converts the values in X to type uint64. Values outside the range [0, 264–1] map to the nearest endpoint.

### Input Arguments

expand all

Input array, specified as a scalar, vector, matrix, or multidimensional array.

Data Types: double | single | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | logical | char

## Examples

collapse all

Convert a double-precision variable to a 64-bit unsigned integer.

x = 100;
xtype = class(x)
xtype =
'double'
y = uint64(x)
y = uint64
100

Convert an array of large integers (larger than flintmax) to a 64-bit unsigned integer array. When you specify a numeric array input, precision can be lost because MATLAB initially represents the input as double precision by default.

Y_inaccurate = uint64([72057594037539387 72057594037927935])
Y_inaccurate = 1x2 uint64 row vector

72057594037539384   72057594037927936

To maintain precision when creating a 64-bit unsigned integer array, call uint64 with each scalar element instead.

Y_accurate = [uint64(72057594037539387) uint64(72057594037927935)]
Y_accurate = 1x2 uint64 row vector

72057594037539387   72057594037927935

Starting in R2019b, you can also create the integer array accurately by using the hexadecimal or binary values of the integers. For more information, see Hexadecimal and Binary Values.

Y_accurate = [0xFFFFFFFFFA123Bu64 0xFFFFFFFFFFFFFFu64]
Y_accurate = 1x2 uint64 row vector

72057594037539387   72057594037927935

## Tips

• When you create a numeric array of large integers (larger than flintmax), MATLAB initially represents the input as double precision by default. Precision can be lost when you convert this input to the uint64 data type. To maintain precision, call uint64 with each scalar element of the array instead. For example, see Convert Array of Large Integers Without Loss of Precision.

• If you have a text formatted in a character array or string scalar that contains large integers, then you can read this text and return an accurate 64-bit unsigned integer array by using the sscanf function. You can specify the format of the input fields so that sscanf directly converts the text that represents integers in decimals, octals, or hexadecimals without first converting them to Unicode code values. For comparison, uint64(X) converts a character vector input to an integer array that represents the Unicode code values for each character.

## Version History

Introduced before R2006a