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To demonstrate the value of the escape sequence feature, to output the text Foo on one line and Bar on the next line, the code must output a newline between the two words. The following code achieves the goal via text formatting and a hard-coded ASCII character value for newline (0x0A). This behaves as desired with the words on sequential lines ...
If the terminating character is a letter, the letter is the keycode value, and the optional number is the modifier value. The modifier value defaults to 1, and after subtracting 1 is a bitmap of modifier keys being pressed: Meta+Ctrl+Alt+⇧ Shift. So, for example, <esc>[4;2~ is ⇧ Shift+End, <esc>[20~ is function key F9, <esc>[5C is Ctrl+→.
This means a string cannot contain the zero code unit, as the first one seen marks the end of the string. The length of a string is the number of code units before the zero code unit. [1] The memory occupied by a string is always one more code unit than the length, as space is needed to store the zero terminator.
In C and many derivative programming languages, a string escape sequence is a series of two or more characters, starting with a backslash \. [3]Note that in C a backslash immediately followed by a newline does not constitute an escape sequence, but splices physical source lines into logical ones in the second translation phase, whereas string escape sequences are converted in the fifth ...
Both character termination and length codes limit strings: For example, C character arrays that contain null (NUL) characters cannot be handled directly by C string library functions: Strings using a length code are limited to the maximum value of the length code. Both of these limitations can be overcome by clever programming.
ASCII codes represent text in computers, telecommunications equipment, and other devices. ASCII has just 128 code points, of which only 95 are printable characters, which severely limit its scope. The set of available punctuation had significant impact on the syntax of computer languages and text markup.
For example, an ASCII (or extended ASCII) scheme will use a single byte of computer memory, while a UTF-8 scheme will use one or more bytes, depending on the particular character being encoded. Alternative ways to encode character values include specifying an integer value for a code point, such as an ASCII code value or a Unicode code point.
The NULL character (code 0) is represented by Ctrl-@, "@" being the code immediately before "A" in the ASCII character set. For convenience, some terminals accept Ctrl-Space as an alias for Ctrl-@. In either case, this produces one of the 32 ASCII control codes between 0 and 31.