UTF-32
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| − | '''UCS Transformation Format—32-bit''' (UTF-32 | + | '''UCS Transformation Format—32-bit''' ('''UTF-32''') is the trivial 32-bit [[Unicode]] character encoding. There is a one-to-one mapping of Unicode code points to 32-bit values, so all characters require the same number of bits. Since the largest code points can be expressed in only 21 bits, this encoding is inherently wasteful of space; [[UTF-8]] or [[UTF-16]] is a more efficient coding in most cases. UTF-32 does provide computational simplicity and is more often used for in-memory storage of characters than for stored documents. |
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| + | UTF-32 is also known as '''UCS-4'''. There may be some subtle philosophical differences between the terms "UTF-32" and "UCS-4", but for all practical purposes they are synonyms. | ||
As with UTF-16, this format exists in both big- and small-[[Endianness|endian]] varieties; since the relevant units are 32-bit chunks (not pairs of 16-bit chunks as the longer sequences of UTF-16 are), the endianness is applied to the entire 32 bits (4 bytes), meaning that the [[Byte Order Mark]] (zero-width no-break space) U+FEFF is encoded as byte sequence 00 00 FE FF in the big-endian version and FF FE 00 00 in the little-endian one (with all four bytes reversed from one version to the other). | As with UTF-16, this format exists in both big- and small-[[Endianness|endian]] varieties; since the relevant units are 32-bit chunks (not pairs of 16-bit chunks as the longer sequences of UTF-16 are), the endianness is applied to the entire 32 bits (4 bytes), meaning that the [[Byte Order Mark]] (zero-width no-break space) U+FEFF is encoded as byte sequence 00 00 FE FF in the big-endian version and FF FE 00 00 in the little-endian one (with all four bytes reversed from one version to the other). | ||
Revision as of 21:43, 14 April 2016
UCS Transformation Format—32-bit (UTF-32) is the trivial 32-bit Unicode character encoding. There is a one-to-one mapping of Unicode code points to 32-bit values, so all characters require the same number of bits. Since the largest code points can be expressed in only 21 bits, this encoding is inherently wasteful of space; UTF-8 or UTF-16 is a more efficient coding in most cases. UTF-32 does provide computational simplicity and is more often used for in-memory storage of characters than for stored documents.
UTF-32 is also known as UCS-4. There may be some subtle philosophical differences between the terms "UTF-32" and "UCS-4", but for all practical purposes they are synonyms.
As with UTF-16, this format exists in both big- and small-endian varieties; since the relevant units are 32-bit chunks (not pairs of 16-bit chunks as the longer sequences of UTF-16 are), the endianness is applied to the entire 32 bits (4 bytes), meaning that the Byte Order Mark (zero-width no-break space) U+FEFF is encoded as byte sequence 00 00 FE FF in the big-endian version and FF FE 00 00 in the little-endian one (with all four bytes reversed from one version to the other).
