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Printf
printf is a C standard library function that formats text and writes it to standard output. The function accepts a format c-string argument and a variable number of value arguments that the function serializes per the format string. Mismatch between the format specifiers and count and type of values results in undefined behavior and possibly program crash or other vulnerability. The format string is encoded as a template language consisting of verbatim text and ''format specifiers'' that each specify how to serialize a value. As the format string is processed left-to-right, a subsequent value is used for each format specifier found. A format specifier starts with a character and has one or more following characters that specify how to serialize a value. The standard library provides other, similar functions that form a family of ''printf-like'' functions. The functions share the same formatting capabilities but provide different behavior such as output to a differen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scanf
scanf, short for scan formatted, is a C standard library function that reads and parses text from standard input. The function accepts a format string parameter that specifies the layout of input text. The function parses input text and loads values into variables based on data type. Similar functions, with other names, predate C, such as readf in ALGOL 68. Input format strings are complementary to output format strings (see printf), which provide formatted output ( templating). History Mike Lesk's portable input/output library, including scanf, officially became part of Unix in Version 7. Usage The scanf function reads input for numbers and other datatypes from standard input. The following C code reads a variable number of unformatted decimal integers from standard input and prints each of them out on separate lines: #include int main(void) For input: 456 123 789 456 12 456 1 2378 The output is: 456 123 789 456 12 456 1 2378 To print out a wo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C Standard Library
The C standard library, sometimes referred to as libc, is the standard library for the C (programming language), C programming language, as specified in the ISO C standard.International Organization for Standardization, ISO/International Electrotechnical Commission, IEC (2018). ''C17 (C standard revision), ISO/IEC 9899:2018(E): Programming Languages - C ยง7'' Starting from the original ANSI C standard, it was developed at the same time as the C POSIX library, which is a superset of it. Since ANSI C was adopted by the International Organization for Standardization, the C standard library is also called the ISO C library. The C standard library provides macro (computer science), macros, Data type, type definitions and Function (computer programming), functions for tasks such as character string (computer science), string manipulation, mathematical computation, input/output processing, memory management, and input/output. Application programming interface (API) Header files The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Percent Sign
The percent sign (sometimes per cent sign in British English) is the symbol used to indicate a percentage, a number or ratio as a fraction (mathematics), fraction of 100. Related signs include the permille (per thousand) sign and the Basis point#Permyriad, permyriad (per ten thousand) sign (also known as a basis point), which indicate that a number is divided by one thousand or ten thousand, respectively. Higher proportions use parts-per notation. Correct style Form and spacing English style guides prescribe writing the percent sign following the number without any space between (e.g. 50%). However, the International System of Units and ISO 31-0 standard prescribe a space between the number and percent sign, in line with the general practice of using a non-breaking space between a numerical value and its corresponding unit of measurement. Other languages have other rules for spacing in front of the percent sign: * In Czech language, Czech and in Slovak language, S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Template Language
A template processor (also known as a template engine or template parser) is software designed to combine ''template''s with data (defined by a data model) to produce resulting Electronic document, documents or Computer program, programs. The language that the templates are written in is known as a template language or templating language. For purposes of this article, a result document is any kind of formatted output, including documents, web pages, or source code (in source code generation), either in whole or in fragments. A template engine is ordinarily included as a part of a web template system or application framework, and may be used also as a preprocessor or Filter (software), filter. Typical features Template engines typically include features common to most High-level programming language, high-level programming languages, with an emphasis on features for processing plain text. Such features include: *variable (programming), variables and Function (computer science) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syntax (programming Languages)
In computer science, the syntax of a computer language is the rules that define the combinations of symbols that are considered to be correctly structured Statement (computer science), statements or Expression (computer science), expressions in that language. This applies both to programming languages, where the document represents source code, and to markup languages, where the document represents data. The syntax of a language defines its surface form. Text-based user interface, Text-based computer languages are based on sequences of Character (computing), characters, while visual programming languages are based on the spatial layout and connections between symbols (which may be textual or graphical). Documents that are syntactically invalid are said to have a syntax error. When designing the syntax of a language, a designer might start by writing down examples of both legal and illegal String (computer science), strings, before trying to figure out the general rules from these ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
String (computer Science)
In computer programming, a string is traditionally a sequence of character (computing), characters, either as a literal (computer programming), literal constant or as some kind of Variable (computer science), variable. The latter may allow its elements to be Immutable object, mutated and the length changed, or it may be fixed (after creation). A string is often implemented as an array data structure of bytes (or word (computer architecture), words) that stores a sequence of elements, typically characters, using some character encoding. More general, ''string'' may also denote a sequence (or List (abstract data type), list) of data other than just characters. Depending on the programming language and precise data type used, a variable (programming), variable declared to be a string may either cause storage in memory to be statically allocated for a predetermined maximum length or employ dynamic allocation to allow it to hold a variable number of elements. When a string appears lit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Undefined Behavior
In computer programming, a program exhibits undefined behavior (UB) when it contains, or is executing code for which its programming language specification does not mandate any specific requirements. This is different from unspecified behavior, for which the language specification does not prescribe a result, and implementation-defined behavior that defers to the documentation of another component of the platform (such as the ABI or the translator documentation). In the C programming community, undefined behavior may be humorously referred to as "nasal demons", after a comp.std.c post that explained undefined behavior as allowing the compiler to do anything it chooses, even "to make demons fly out of your nose". Overview Some programming languages allow a program to operate differently or even have a different control flow from the source code, as long as it exhibits the same user-visible side effects, ''if undefined behavior never happens during program execution''. Undef ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parsing
Parsing, syntax analysis, or syntactic analysis is a process of analyzing a String (computer science), string of Symbol (formal), symbols, either in natural language, computer languages or data structures, conforming to the rules of a formal grammar by breaking it into parts. The term ''parsing'' comes from Latin ''pars'' (''orationis''), meaning Part of speech, part (of speech). The term has slightly different meanings in different branches of linguistics and computer science. Traditional Sentence (linguistics), sentence parsing is often performed as a method of understanding the exact meaning of a sentence or word, sometimes with the aid of devices such as sentence diagrams. It usually emphasizes the importance of grammatical divisions such as subject (grammar), subject and predicate (grammar), predicate. Within computational linguistics the term is used to refer to the formal analysis by a computer of a sentence or other string of words into its constituents, resulting in a par ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Function (computer Programming)
In computer programming, a function (also procedure, method, subroutine, routine, or subprogram) is a callable unit of software logic that has a well-defined interface and behavior and can be invoked multiple times. Callable units provide a powerful programming tool. The primary purpose is to allow for the decomposition of a large and/or complicated problem into chunks that have relatively low cognitive load and to assign the chunks meaningful names (unless they are anonymous). Judicious application can reduce the cost of developing and maintaining software, while increasing its quality and reliability. Callable units are present at multiple levels of abstraction in the programming environment. For example, a programmer may write a function in source code that is compiled to machine code that implements similar semantics. There is a callable unit in the source code and an associated one in the machine code, but they are different kinds of callable units with different impl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic-tape Data Storage
Magnetic-tape data storage is a system for storing digital information on magnetic tape using digital recording. Tape was an important medium for primary data storage in early computers, typically using large open reels of 7-track, later 9-track tape. Modern magnetic tape is most commonly packaged in cartridges and cassettes, such as the widely supported Linear Tape-Open (LTO) and IBM 3592 series. The device that performs the writing or reading of data is called a tape drive. Autoloaders and tape libraries are often used to automate cartridge handling and exchange. Compatibility was important to enable transferring data. Tape data storage is now used more for system backup, data archive and data exchange. The low cost of tape has kept it viable for long-term storage and archive. Open reels Initially, magnetic tape for data storage was wound on reels. This standard for large computer systems persisted through the late 1980s, with steadily increasing capacity d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Line Printer
A line printer Printer (computing), prints one entire line of text before advancing to another line. Most early line printers were printer (computing)#Impact printers, impact printers. Line printers are mostly associated with unit record equipment and the early days of digital computing, but the technology is still in use. Print speeds of 600 lines per minute (approximately 10 pages per minute) were achieved in the 1950s, later increasing to as much as 1200 lpm. Line printers print a complete line at a time and have speeds in the range of 150 to 2500 lines per minute. Some types of impact line printers are #Drum printer, drum printers, #Band printer, band-printers, and #Chain printer, chain printers. Non-impact technologies have also been used, e.g., thermal printing, thermal line printers were popular in the 1970s and 1980s, some inkjet and laser printers produce output a line or a page at a time. Designs Many impact printers, such as the daisywheel printer and dot matri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
