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Only a small subset of possible byte strings are error-free UTF-8: several bytes cannot appear; a byte with the high bit set cannot be alone; and in a truly random string a byte with a high bit set has only a 1 ⁄ 15 chance of starting a valid UTF-8 character. This has the (possibly unintended) consequence of making it easy to detect if a ...
UTF-8 and Shift JIS are often used in C byte strings, while UTF-16 is often used in C wide strings when wchar_t is 16 bits. Truncating strings with variable-width characters using functions like strncpy can produce invalid sequences at the end of the string. This can be unsafe if the truncated parts are interpreted by code that assumes the ...
This has led to character encoding systems such as UTF-8 that can use multiple bytes to encode a value that is too large for a single 8-bit symbol. The C standard distinguishes between multibyte encodings of characters, which use a fixed or variable number of bytes to represent each character (primarily used in source code and external files ...
UTF-8-encoded, preceded by 32-bit integer length of string in bytes Vectors of any other type, preceded by 32-bit integer length of number of elements Tables (schema defined types) or Vectors sorted by key (maps / dictionaries)
An std::string can be constructed from a C-style string, and a C-style string can also be obtained from one. [7] The individual units making up the string are of type char, at least (and almost always) 8 bits each. In modern usage these are often not "characters", but parts of a multibyte character encoding such as UTF-8.
UTF-8, UTF-16, UTF-32 and UTF-EBCDIC have these important properties but UTF-7 and GB 18030 do not. Fixed-size characters can be helpful, but even if there is a fixed byte count per code point (as in UTF-32), there is not a fixed byte count per displayed character due to combining characters .
A char in the C programming language is a data type with the size of exactly one byte, [6] [7] which in turn is defined to be large enough to contain any member of the "basic execution character set". The exact number of bits can be checked via CHAR_BIT macro. By far the most common size is 8 bits, and the POSIX standard requires it to be 8 ...
Some systems use "modified UTF-8" which encodes NUL as two non-zero bytes (0xC0, 0x80) and thus allow all possible strings to be stored. This is not allowed by the UTF-8 standard, because it is an overlong encoding, and it is seen as a security risk. Some other byte may be used as end of string instead, like 0xFE or 0xFF, which are not used in ...