Difference between revisions of "Data types"
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Drainedsoul (talk | contribs) (Terminology clean up) |
(bool moved before byte as that it carries less information quantity) |
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! class="col3" | Notes | ! class="col3" | Notes | ||
|- class="row1" | |- class="row1" | ||
| + | ! class="col0 centeralign" | bool | ||
| + | | class="col1 centeralign" | 1 | ||
| + | | class="col2" | 0 or 1 | ||
| + | | class="col3" | Value can be either true (0x01) or false (0x00) | ||
| + | |- class="row2" | ||
! class="col0 centeralign" | byte | ! class="col0 centeralign" | byte | ||
| class="col1 centeralign" | 1 | | class="col1 centeralign" | 1 | ||
| class="col2" | -128 to 127 | | class="col2" | -128 to 127 | ||
| class="col3" | Signed, two's complement | | class="col3" | Signed, two's complement | ||
| − | |- class=" | + | |- class="row3" |
! class="col0 centeralign" | short | ! class="col0 centeralign" | short | ||
| class="col1 centeralign" | 2 | | class="col1 centeralign" | 2 | ||
| class="col2" | -32768 to 32767 | | class="col2" | -32768 to 32767 | ||
| class="col3" | Signed, two's complement | | class="col3" | Signed, two's complement | ||
| − | |- class=" | + | |- class="row4" |
! class="col0 centeralign" | int | ! class="col0 centeralign" | int | ||
| class="col1 centeralign" | 4 | | class="col1 centeralign" | 4 | ||
| class="col2" | -2147483648 to 2147483647 | | class="col2" | -2147483648 to 2147483647 | ||
| class="col3" | Signed, two's complement | | class="col3" | Signed, two's complement | ||
| − | |- class=" | + | |- class="row5" |
! class="col0 centeralign" | long | ! class="col0 centeralign" | long | ||
| class="col1 centeralign" | 8 | | class="col1 centeralign" | 8 | ||
| class="col2" | -9223372036854775808 to 9223372036854775807 | | class="col2" | -9223372036854775808 to 9223372036854775807 | ||
| class="col3" | Signed, two's complement | | class="col3" | Signed, two's complement | ||
| − | |- class=" | + | |- class="row6" |
! class="col0 centeralign" | float | ! class="col0 centeralign" | float | ||
| class="col1 centeralign" | 4 | | class="col1 centeralign" | 4 | ||
| Line 35: | Line 40: | ||
See [http://java.sun.com/docs/books/jls/third_edition/html/typesValues.html#4.2.3 this] | See [http://java.sun.com/docs/books/jls/third_edition/html/typesValues.html#4.2.3 this] | ||
| class="col3" | Single-precision 32-bit IEEE 754 floating point | | class="col3" | Single-precision 32-bit IEEE 754 floating point | ||
| − | |- class=" | + | |- class="row7" |
! class="col0 centeralign" | double | ! class="col0 centeralign" | double | ||
| class="col1 centeralign" | 8 | | class="col1 centeralign" | 8 | ||
| Line 41: | Line 46: | ||
See [http://java.sun.com/docs/books/jls/third_edition/html/typesValues.html#4.2.3 this] | See [http://java.sun.com/docs/books/jls/third_edition/html/typesValues.html#4.2.3 this] | ||
| class="col3" | Double-precision 64-bit IEEE 754 floating point | | class="col3" | Double-precision 64-bit IEEE 754 floating point | ||
| − | |- class=" | + | |- class="row8" |
! class="col0 centeralign" | string | ! class="col0 centeralign" | string | ||
| class="col1 centeralign" | ≥ 2 <br />≤ 240 | | class="col1 centeralign" | ≥ 2 <br />≤ 240 | ||
| class="col2" | N/A | | class="col2" | N/A | ||
| class="col3" | [http://en.wikipedia.org/wiki/UTF-16/UCS-2 UCS-2] big-endian string prefixed by a short containing the length of the string in [http://en.wikipedia.org/wiki/Code_point code points]. UCS-2 is a fixed-width encoding with each code point represented by a 16-bit code unit. As it is limited to 16 bits it can only represent code points in the [https://en.wikipedia.org/wiki/Plane_(Unicode)#Basic_Multilingual_Plane Basic Multilangual Plane] (U+0000 through U+FFFF inclusive). | | class="col3" | [http://en.wikipedia.org/wiki/UTF-16/UCS-2 UCS-2] big-endian string prefixed by a short containing the length of the string in [http://en.wikipedia.org/wiki/Code_point code points]. UCS-2 is a fixed-width encoding with each code point represented by a 16-bit code unit. As it is limited to 16 bits it can only represent code points in the [https://en.wikipedia.org/wiki/Plane_(Unicode)#Basic_Multilingual_Plane Basic Multilangual Plane] (U+0000 through U+FFFF inclusive). | ||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
|- class="row9" | |- class="row9" | ||
! class="col0 centeralign" | metadata | ! class="col0 centeralign" | metadata | ||
Revision as of 05:10, 18 July 2013
All data sent over the network is big-endian, that is the bytes are sent from most significant byte to least significant byte. The majority of everyday computers are little-endian, therefore it may be necessary to change the endianness before sending data over the network.
Other than 'String' and 'Metadata', which are decoded with a custom function, these data formats are identical to those provided by the Java classes DataInputStream and DataOutputStream.
| Size | Range | Notes | |
|---|---|---|---|
| bool | 1 | 0 or 1 | Value can be either true (0x01) or false (0x00) |
| byte | 1 | -128 to 127 | Signed, two's complement |
| short | 2 | -32768 to 32767 | Signed, two's complement |
| int | 4 | -2147483648 to 2147483647 | Signed, two's complement |
| long | 8 | -9223372036854775808 to 9223372036854775807 | Signed, two's complement |
| float | 4 |
See this |
Single-precision 32-bit IEEE 754 floating point |
| double | 8 |
See this |
Double-precision 64-bit IEEE 754 floating point |
| string | ≥ 2 ≤ 240 |
N/A | UCS-2 big-endian string prefixed by a short containing the length of the string in code points. UCS-2 is a fixed-width encoding with each code point represented by a 16-bit code unit. As it is limited to 16 bits it can only represent code points in the Basic Multilangual Plane (U+0000 through U+FFFF inclusive). |
| metadata | Varies | See this |
Some data may be stored as an "absolute integer", which is a more precise kind of integer, and a less precise kind of double. The conversion from double to absolute integer is like so:
abs_int = (int)double * 32;
And back again:
double = (double)abs_int / 32;
