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Null-terminated strings require that the encoding does not use a zero byte (0x00) anywhere; therefore it is not possible to store every possible ASCII or UTF-8 string. [ 8 ] [ 9 ] [ 10 ] However, it is common to store the subset of ASCII or UTF-8 – every character except NUL – in null-terminated strings.
The ability to represent a null character does not always mean the resulting string will be correctly interpreted, as many programs will consider the null to be the end of the string. Thus the ability to type it (in case of unchecked user input) creates a vulnerability known as null byte injection and can lead to security exploits. [10]
For example, the null character (U+0000 NULL) is used in C-programming application environments to indicate the end of a string of characters. In this way, these programs only require a single starting memory address for a string (as opposed to a starting address and a length), since the string ends once the program reads the null character.
Some three-digit octal escape sequences are too large to fit in a single byte. This results in an implementation-defined value for the resulting byte. The escape sequence \0 is a commonly used octal escape sequence, which denotes the null character, with value zero in ASCII and most encoding systems.
0x00 (null, NUL, \0, ^@), originally intended to be an ignored character, but now used by many programming languages including C to mark the end of a string. 0x07 (bell, BEL, \a, ^G), which may cause the device to emit a warning such as a bell or beep sound or the screen flashing. 0x08 (backspace, BS, \b, ^H), may overprint the previous character.
The BSD documentation has been fixed to make this clear, but POSIX, Linux, and Windows documentation still uses "character" in many places where "byte" or "wchar_t" is the correct term. Functions for handling memory buffers can process sequences of bytes that include null-byte as part of the data.
People often use the simple mnemonic spring forward, fall back to remember to set clocks forward one hour (e.g., from 2 a.m. to 3 a.m.) in the spring and backward one hour (e.g., from 2 a.m. to 1 ...
Generally, an escape character is not a particular case of (device) control characters, nor vice versa.If we define control characters as non-graphic, or as having a special meaning for an output device (e.g. printer or text terminal) then any escape character for this device is a control one.