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While(true)
In computer programming, an infinite loop (or endless loop) is a sequence of instructions that, as written, will continue endlessly, unless an external intervention occurs, such as turning off power via a switch or pulling a plug. It may be intentional. There is no general algorithm to determine whether a computer program contains an infinite loop or not; this is the halting problem. Overview This differs from "a type of computer program that runs the same instructions continuously until it is either stopped or interrupted". Consider the following pseudocode: how_many = 0 while is_there_more_data() do how_many = how_many + 1 end display "the number of items counted = " how_many ''The same instructions'' were run ''continuously until it was stopped or interrupted'' . . . by the ''FALSE'' returned at some point by the function ''is_there_more_data''. By contrast, the following loop will not end by itself: birds = 1 fish = 2 while birds + fish > 1 do birds = 3 - birds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Do While Loop
In many computer programming Programming language, languages, a do while loop is a control flow Statement (computer science), statement that executes a block of code and then either repeats the block or exits the loop depending on a given Boolean data type, boolean condition. The ''do while'' construct consists of a process symbol and a condition. First the code within the block is executed. Then the condition is evaluated. If the condition is Truth, true the code within the block is executed again. This repeats until the condition becomes False (logic), false. Do while loops check the condition after the block of code is executed. This control structure can be known as a post-test loop. This means the do-while loop is an exit-condition loop. However a while loop will test the condition before the code within the block is executed. This means that the code is always executed first and then the expression or test condition is evaluated. This process is repeated as long as the ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blue Screen Of Death
The blue screen of death (BSoD) or blue screen error, blue screen, fatal error, bugcheck, and officially known as a stop erroris a fatal system error, critical error screen displayed by the Microsoft Windows operating systems to indicate a crash (computing), system crash, in which the operating system reaches a critical condition where it can no longer operate safely. The name comes from the blue colored background used predominately on the error screens found in the majority of Windows releases. Possible issues contributing to a BSoD may include hardware failures, an issue with or without a device driver, computer virus, viruses, malware, and other factors such as intentional user action. __TOC__ History Blue screen errors have been around since the very first version of Windows in 1985. In the Beta Release of Windows 1.0, if it detected a version of DOS that is newer than the OS expects, the boot screen would have the text "Incorrect DOS version" alongside other messages ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Control-C
Control-C is a common command (computing), computer command. It is generated by holding down the key and typing the key. In graphical user interface environments, control+C is often used to Cut, copy and paste, copy highlighted text to the Clipboard (software), clipboard. Macintosh computers use for this. In many command-line interface environments, control+C is used to abort (computing), abort the current task and regain user control. In graphical environments Larry Tesler created the concept of Cut, copy, and paste, cut, copy, paste, and undo for human-computer interaction while working at Xerox PARC to control text editor, text editing. During the development of the Macintosh it was decided that the cut, paste, copy and undo would be used frequently and assigned them to the Command Key, ⌘-Z (Undo), ⌘-X (Cut), ⌘-C (Copy), and ⌘-V (Paste). The four letters are all located together at the left end of the bottom row of the standard QWERTY keyboard. IBM and early ver ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Task Manager
In operating systems, a task manager is a system monitor program used to provide information about the processes and applications running on a computer, as well as the general status of the computer. Some implementations can also be used to terminate processes and applications, as well as change the processes' scheduling priority. In some environments, users can access a task manager with the Control-Alt-Delete keyboard shortcut. Task managers can display running services. ( processes) as well as those that were stopped. They can display information about the services, including their process identifier and group identifier. Common task managers * Activity Monitor, included in macOS * Conky, for the X Window System * htop, for the Unix shell * Plasma System Monitor, included in KDE Plasma Desktop * nmon, for Linux and AIX * ps, for the Unix shell * Task Manager, included in Windows * tasklist, for DOS * TaskManager, included in MorphOS * top, for the Unix shell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interrupt
In digital computers, an interrupt (sometimes referred to as a trap) is a request for the processor to ''interrupt'' currently executing code (when permitted), so that the event can be processed in a timely manner. If the request is accepted, the processor will suspend its current activities, save its state, and execute a function called an '' interrupt handler'' (or an ''interrupt service routine'', ISR) to deal with the event. This interruption is often temporary, allowing the software to resume normal activities after the interrupt handler finishes, although the interrupt could instead indicate a fatal error. Interrupts are commonly used by hardware devices to indicate electronic or physical state changes that require time-sensitive attention. Interrupts are also commonly used to implement computer multitasking and system calls, especially in real-time computing. Systems that use interrupts in these ways are said to be interrupt-driven. History Hardware interrupts wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SIGINT (POSIX)
Signals are standardized messages sent to a running program to trigger specific behavior, such as quitting or error handling. They are a limited form of inter-process communication (IPC), typically used in Unix, Unix-like, and other POSIX-compliant operating systems. A signal is an asynchronous notification sent to a process or to a specific thread within the same process to notify it of an event. Common uses of signals are to interrupt, suspend, terminate or kill a process. Signals originated in 1970s Bell Labs Unix and were later specified in the POSIX standard. When a signal is sent, the operating system interrupts the target process's normal flow of execution to deliver the signal. Execution can be interrupted during any non-atomic instruction. If the process has previously registered a signal handler, that routine is executed. Otherwise, the default signal handler is executed. Embedded programs may find signals useful for inter-process communications, as signals ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Undecidable Problem
In computability theory and computational complexity theory, an undecidable problem is a decision problem for which it is proved to be impossible to construct an algorithm that always leads to a correct yes-or-no answer. The halting problem is an example: it can be proven that there is no algorithm that correctly determines whether an arbitrary program eventually halts when run. Background A decision problem is a question which, for every input in some infinite set of inputs, requires a "yes" or "no" answer. Those inputs can be numbers (for example, the decision problem "is the input a prime number?") or values of some other kind, such as strings of a formal language. The formal representation of a decision problem is a subset of the natural numbers. For decision problems on natural numbers, the set consists of those numbers that the decision problem answers "yes" to. For example, the decision problem "is the input even?" is formalized as the set of even numbers. A decision pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ring (data Structure)
In computer science, a circular buffer, circular queue, cyclic buffer or ring buffer is a data structure that uses a single, fixed-size buffer as if it were connected end-to-end. This structure lends itself easily to buffering data streams. There were early circular buffer implementations in hardware. Overview A circular buffer first starts out empty and has a set length. In the diagram below is a 7-element buffer: : Assume that 1 is written in the center of a circular buffer (the exact starting location is not important in a circular buffer): : Then assume that two more elements are added to the circular buffer — 2 & 3 — which get put after 1: : If two elements are removed, the two oldest values inside of the circular buffer would be removed. Circular buffers use FIFO ('' first in, first out'') logic. In the example, 1 & 2 were the first to enter the circular buffer, they are the first to be removed, leaving 3 inside of the buffer. : If the buffer has 7 el ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tree (data Structure)
In computer science, a tree is a widely used abstract data type that represents a hierarchical tree structure with a set of connected nodes. Each node in the tree can be connected to many children (depending on the type of tree), but must be connected to exactly one parent, except for the ''root'' node, which has no parent (i.e., the root node as the top-most node in the tree hierarchy). These constraints mean there are no cycles or "loops" (no node can be its own ancestor), and also that each child can be treated like the root node of its own subtree, making recursion a useful technique for tree traversal. In contrast to linear data structures, many trees cannot be represented by relationships between neighboring nodes (parent and children nodes of a node under consideration, if they exist) in a single straight line (called edge or link between two adjacent nodes). Binary trees are a commonly used type, which constrain the number of children for each parent to at most two. Whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linked List
In computer science, a linked list is a linear collection of data elements whose order is not given by their physical placement in memory. Instead, each element points to the next. It is a data structure consisting of a collection of nodes which together represent a sequence. In its most basic form, each node contains data, and a reference (in other words, a ''link'') to the next node in the sequence. This structure allows for efficient insertion or removal of elements from any position in the sequence during iteration. More complex variants add additional links, allowing more efficient insertion or removal of nodes at arbitrary positions. A drawback of linked lists is that data access time is linear in respect to the number of nodes in the list. Because nodes are serially linked, accessing any node requires that the prior node be accessed beforehand (which introduces difficulties in pipelining). Faster access, such as random access, is not feasible. Arrays have better cache ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Structure
In computer science, a data structure is a data organization and storage format that is usually chosen for Efficiency, efficient Data access, access to data. More precisely, a data structure is a collection of data values, the relationships among them, and the Function (computer programming), functions or Operator (computer programming), operations that can be applied to the data, i.e., it is an algebraic structure about data. Usage Data structures serve as the basis for abstract data types (ADT). The ADT defines the logical form of the data type. The data structure implements the physical form of the data type. Different types of data structures are suited to different kinds of applications, and some are highly specialized to specific tasks. For example, Relational database, relational databases commonly use B-tree indexes for data retrieval, while compiler Implementation, implementations usually use hash tables to look up Identifier (computer languages), identifiers. Data s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Bug
A software bug is a design defect ( bug) in computer software. A computer program with many or serious bugs may be described as ''buggy''. The effects of a software bug range from minor (such as a misspelled word in the user interface) to severe (such as frequent crashing). In 2002, a study commissioned by the US Department of Commerce's National Institute of Standards and Technology concluded that "software bugs, or errors, are so prevalent and so detrimental that they cost the US economy an estimated $59 billion annually, or about 0.6 percent of the gross domestic product". Since the 1950s, some computer systems have been designed to detect or auto-correct various software errors during operations. History Terminology ''Mistake metamorphism'' (from Greek ''meta'' = "change", ''morph'' = "form") refers to the evolution of a defect in the final stage of software deployment. Transformation of a ''mistake'' committed by an analyst in the early stages of the softw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
