Substitute character

In computer data, a substitute character (␚) is a control character that is used to pad transmitted data in order to send it in blocks of fixed size, or to stand in place of a character that is recognized to be invalid, erroneous or unrepresentable on a given device. It is also used as an escape sequence in some programming languages. In the ASCII character set, this character is encoded by the number 26 ( hex). Standard keyboards transmit this code when the and keys are pressed simultaneously (, often documented by convention as ). Unicode inherits this character from ASCII, but recommends that the replacement character (�, U+FFFD) be used instead to represent un-decodable inputs, when the output encoding is compatible with it. End-of-file Historically, under PDP-6 monitor, RT-11, VMS, and TOPS-10, and in early PC CP/M 1 and 2 operating systems (and derivatives like MP/M) it was necessary to explicitly mark the (EOF) because the native could not record the exact file size by itself; files were allocated in extents (records) of a fixed size, typically leaving some allocated but unused space at the end of each file. This extra space was filled with 16 (hex) characters under CP/M. The extended CP/M filesystems used by CP/M 3 and higher (and derivatives like Concurrent CP/M, Concurrent DOS, and DOS Plus) did support byte-granular files, so this was no longer a requirement, but it remained as a convention (especially for s) in order to ensure backward compatibility. In CP/M, 86-DOS, MS-DOS, PC DOS, DR-DOS, and their various derivatives, the SUB character was also used to indicate the end of a character stream, and thereby used to terminate user input in an interactive command line window (and as such, often used to finish console input redirection, e.g. as instigated by the command ). While no longer technically required to indicate the end of a file, as of 2017 many text editors and program languages still support this convention, or can be configured to insert this character at the end of a file when editing, or at least properly cope with them in text files.

About this result

This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.

Related publications (1)

Related concepts (5)

Related lectures (7)

Resolution-independent windowing systems and raster image processors require efficient and precise rendering of outline characters. Rendering of typographic outline characters involves outline grid fitting, outline scan conversion, and filling. For the pur ...

1991

Control-C

Control-C is a common computer command. It is generated by pressing the key while holding down the key on most computer keyboards. In graphical user interface environments that use the control key to control the active program, control+C is often used to copy highlighted text to the clipboard. In many command-line interface environments, control+C is used to abort the current task and regain user control. It is a special sequence that causes the operating system to send a signal to the active program.

UTF-8

UTF-8 is a variable-length character encoding standard used for electronic communication. Defined by the Unicode Standard, the name is derived from Unicode (or Universal Coded Character Set) Transformation Format - 8-bit. UTF-8 is capable of encoding all 1,112,064 valid character code points in Unicode using one to four one-byte (8-bit) code units. Code points with lower numerical values, which tend to occur more frequently, are encoded using fewer bytes.

ASCII

ASCII (ˈæskiː ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because of technical limitations of computer systems at the time it was invented, ASCII has just 128 code points, of which only 95 are , which severely limited its scope. Many computer systems instead use Unicode, which has millions of code points, but the first 128 of these are the same as the ASCII set.

Network and Web - communication MOOC: Humanitarian Action in the Digital Age

Covers the basics of networking and web technologies, focusing on communication infrastructures and data representation.

Matlab Strings: Basics and Manipulation

Covers the basics of working with strings in Matlab, including creating, indexing, and manipulating string variables.

Character Encoding: ASCII, ISO 8859-1, Unicode CS-108: Practice of object-oriented programming

Explores the evolution of character encoding standards like ASCII, ISO 8859-1, and Unicode.