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Null Character
The null character (also null terminator) is a control character with the value zero. It is present in many character sets, including those defined by the Baudot and ITA2 codes, ISO/IEC 646 (or ASCII), the C0 control code, the Universal Coded Character Set (or Unicode), and EBCDIC. It is available in nearly all mainstream programming languages. It is often abbreviated as NUL (or NULL, though in some contexts that term is used for the null pointer). In 8-bit codes, it is known as a null byte. The original meaning of this character was like NOP—when sent to a printer or a terminal, it has no effect (some terminals, however, incorrectly display it as space). When electromechanical teleprinters were used as computer output devices, one or more null characters were sent at the end of each printed line to allow time for the mechanism to return to the first printing position on the next line. On punched tape, the character is represented with no holes at all, so a new unpunched ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Control Character
In computing and telecommunication, a control character or non-printing character (NPC) is a code point (a number) in a character set, that does not represent a written symbol. They are used as in-band signaling to cause effects other than the addition of a symbol to the text. All other characters are mainly printing, printable, or graphic characters, except perhaps for the "space" character (see ASCII printable characters). History Procedural signs in Morse code are a form of control character. A form of control characters were introduced in the 1870 Baudot code: NUL and DEL. The 1901 Murray code added the carriage return (CR) and line feed (LF), and other versions of the Baudot code included other control characters. The bell character (BEL), which rang a bell to alert operators, was also an early teletype control character. Control characters have also been called "format effectors". In ASCII There were quite a few control characters defined (33 in ASCII, and the E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Teleprinter
A teleprinter (teletypewriter, teletype or TTY) is an electromechanical device that can be used to send and receive typed messages through various communications channels, in both point-to-point and point-to-multipoint configurations. Initially they were used in telegraphy, which developed in the late 1830s and 1840s as the first use of electrical engineering, though teleprinters were not used for telegraphy until 1887 at the earliest. The machines were adapted to provide a user interface to early mainframe computers and minicomputers, sending typed data to the computer and printing the response. Some models could also be used to create punched tape for data storage (either from typed input or from data received from a remote source) and to read back such tape for local printing or transmission. Teleprinters could use a variety of different communication media. These included a simple pair of wires; dedicated non-switched telephone circuits (leased lines); switched ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Percent Encoding
Percent-encoding, also known as URL encoding, is a method to encode arbitrary data in a Uniform Resource Identifier (URI) using only the limited US-ASCII characters legal within a URI. Although it is known as ''URL encoding'', it is also used more generally within the main Uniform Resource Identifier (URI) set, which includes both Uniform Resource Locator (URL) and Uniform Resource Name (URN). As such, it is also used in the preparation of data of the application/x-www-form-urlencoded media type, as is often used in the submission of HTML form data in HTTP requests. Percent-encoding in a URI Types of URI characters The characters allowed in a URI are either ''reserved'' or ''unreserved'' (or a percent character as part of a percent-encoding). ''Reserved'' characters are those characters that sometimes have special meaning. For example, forward slash characters are used to separate different parts of a URL (or more generally, a URI). ''Unreserved'' characters have no suc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
YAML
YAML ( and ) (''see '') is a human-readable data-serialization language. It is commonly used for configuration files and in applications where data is being stored or transmitted. YAML targets many of the same communications applications as Extensible Markup Language (XML) but has a minimal syntax which intentionally differs from Standard Generalized Markup Language (SGML). It uses both Python-style indentation to indicate nesting, and a more compact format that uses for lists and for maps thus JSON files are valid YAML 1.2. Custom data types are allowed, but YAML natively encodes scalars (such as strings, integers, and floats), lists, and associative arrays (also known as maps, dictionaries or hashes). These data types are based on the Perl programming language, though all commonly used high-level programming languages share very similar concepts. The colon-centered syntax, used for expressing key-value pairs, is inspired by electronic mail headers as defined in , and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Octal
The octal numeral system, or oct for short, is the base-8 number system, and uses the digits 0 to 7. This is to say that 10octal represents eight and 100octal represents sixty-four. However, English, like most languages, uses a base-10 number system, hence a true octal system might use different vocabulary. In the decimal system, each place is a power of ten. For example: : \mathbf_ = \mathbf \times 10^1 + \mathbf \times 10^0 In the octal system, each place is a power of eight. For example: : \mathbf_8 = \mathbf \times 8^2 + \mathbf \times 8^1 + \mathbf \times 8^0 By performing the calculation above in the familiar decimal system, we see why 112 in octal is equal to 64+8+2=74 in decimal. Octal numerals can be easily converted from binary representations (similar to a quaternary numeral system) by grouping consecutive binary digits into groups of three (starting from the right, for integers). For example, the binary representation for decimal 74 is 1001010. Two zeroes ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Escape Sequences In C
Escape sequences are used in the programming languages C and C++, and their design was copied in many other languages such as Java, PHP, C#, etc. An escape sequence is a sequence of characters that does not represent itself when used inside a character or string literal, but is translated into another character or a sequence of characters that may be difficult or impossible to represent directly. In C, all escape sequences consist of two or more characters, the first of which is the backslash, (called the "Escape character"); the remaining characters determine the interpretation of the escape sequence. For example, is an escape sequence that denotes a newline character. Motivation Suppose we want to print out on one line, followed by on the next line. One could attempt to represent the string to be printed as a single literal as follows: #include int main() This is not valid in C, since a string literal may not span multiple logical source lines. This can be worke ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
String Literal
A string literal or anonymous string is a string value in the source code of a computer program. Modern programming languages commonly use a quoted sequence of characters, formally " bracketed delimiters", as in x = "foo", where "foo" is a string literal with value foo. Methods such as escape sequences can be used to avoid the problem of delimiter collision (issues with brackets) and allow the delimiters to be embedded in a string. There are many alternate notations for specifying string literals especially in complicated cases. The exact notation depends on the programming language in question. Nevertheless, there are general guidelines that most modern programming languages follow. Syntax Bracketed delimiters Most modern programming languages use bracket delimiters (also balanced delimiters) to specify string literals. Double quotations are the most common quoting delimiters used: "Hi There!" An empty string is literally written by a pair of quotes with no character a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Source Code
In computing, source code, or simply code, is any collection of code, with or without comments, written using a human-readable programming language, usually as plain text. The source code of a program is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source code. The source code is often transformed by an assembler or compiler into binary machine code that can be executed by the computer. The machine code is then available for execution at a later time. Most application software is distributed in a form that includes only executable files. If the source code were included it would be useful to a user, programmer or a system administrator, any of whom might wish to study or modify the program. Alternatively, depending on the technology being used, source code may be interpreted and executed directly. Definitions Richard Stallman's definition, formulated in his 1989 seminal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Escape Sequence
In computer science, an escape sequence is a combination of characters that has a meaning other than the literal characters contained therein; it is marked by one or more preceding (and possibly terminating) characters. Examples * In C and many derivative programming languages, a string escape sequence is a series of two or more characters, starting with a backslash \. ** 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 translation phase. ** To represent the backslash character itself, \\ can be used, whereby the first backslash indicates an escape and the second specifies that a backslash is being escaped. ** A character may be escaped in multiple different ways. Assuming ASCII encoding, the escape sequences \x5c (hexadecimal), \\, \134 (octal) and \x5C all encode the same character: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Electrotechnical Commission
The International Electrotechnical Commission (IEC; in French: ''Commission électrotechnique internationale'') is an international standards organization that prepares and publishes international standards for all electrical, electronic and related technologies – collectively known as " electrotechnology". IEC standards cover a vast range of technologies from power generation, transmission and distribution to home appliances and office equipment, semiconductors, fibre optics, batteries, solar energy, nanotechnology and marine energy as well as many others. The IEC also manages four global conformity assessment systems that certify whether equipment, system or components conform to its international standards. All electrotechnologies are covered by IEC Standards, including energy production and distribution, electronics, magnetics and electromagnetics, electroacoustics, multimedia, telecommunication and medical technology, as well as associated general disciplines suc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Organization For Standardization
The International Organization for Standardization (ISO ) is an international standard development organization composed of representatives from the national standards organizations of member countries. Membership requirements are given in Article 3 of the ISO Statutes. ISO was founded on 23 February 1947, and (as of November 2022) it has published over 24,500 international standards covering almost all aspects of technology and manufacturing. It has 809 Technical committees and sub committees to take care of standards development. The organization develops and publishes standardization in all technical and nontechnical fields other than Electrical engineering, electrical and electronic engineering, which is handled by the International Electrotechnical Commission, IEC.Editors of Encyclopedia Britannica. 3 June 2021.International Organization for Standardization" ''Encyclopedia Britannica''. Retrieved 2022-04-26. It is headquartered in Geneva, Switzerland, and works in 167 coun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Null-terminated String
In computer programming, a null-terminated string is a character string stored as an array containing the characters and terminated with a null character (a character with a value of zero, called NUL in this article). Alternative names are C string, which refers to the C programming language and ASCIIZ (although C can use encodings other than ASCII). The length of a string is found by searching for the (first) NUL. This can be slow as it takes O(''n'') (linear time) with respect to the string length. It also means that a string cannot contain a NUL (there is a NUL in memory, but it is after the last character, not "in" the string). History Null-terminated strings were produced by the .ASCIZ directive of the PDP-11 assembly languages and the ASCIZ directive of the MACRO-10 macro assembly language for the PDP-10. These predate the development of the C programming language, but other forms of strings were often used. At the time C (and the languages that it was derived from) was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
