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Static Library
A static library or statically linked library contains functions and data that can be included in a consuming computer program at build-time such that the library does not need to be accessible in a separate file at run-time. If all libraries are statically linked, then the resulting executable will be stand-alone, a.k.a. a static build. A static library is either merged with other static libraries and object files at build-time to form a single executable or loaded at run-time into the address space of their corresponding executable at a static memory offset determined at compile-time/link-time. Comparison to dynamic linking Historically, all library linking was static, but today dynamic linking is an alternative and entails inherent trade-offs. An advantage of static over dynamic is that the application is guaranteed to have the library routines it requires available at run-time, as the code to those routines is embedded in the executable file. With dynamic linking, no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Function (computer Science)
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] |
Linking Loader
A linker or link editor is a computer program that combines intermediate software build files such as object and library files into a single executable file such as a program or library. A linker is often part of a toolchain that includes a compiler and/or assembler that generates intermediate files that the linker processes. The linker may be integrated with other toolchain tools such that the user does not interact with the linker directly. A simpler version that writes its output directly to memory is called the ''loader'', though loading is typically considered a separate process. Overview Computer programs typically are composed of several parts or modules; these parts/modules do not need to be contained within a single object file, and in such cases refer to each other using symbols as addresses into other modules, which are mapped into memory addresses when linked for execution. While the process of linking is meant to ultimately combine these independent parts, ther ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prebinding
In computing, prebinding, also called prelinking, is a method for optimizing application load times by resolving library symbols prior to launch. Background Most computer programs consist of code that requires external shared libraries to execute. These libraries are normally integrated with the program at run time by a loader, in a process called dynamic linking. While dynamic linking has advantages in code size and management, there are drawbacks as well. Every time a program is run, the loader needs to resolve (find) the relevant libraries. Since libraries move around in memory, there is a performance penalty for resolution. This penalty increases for each additional library needing resolution. Prelinking reduces this penalty by resolving libraries in advance. Afterward, resolution only occurs if the libraries have changed since being prelinked, such as following perhaps an upgrade. Mac OS Mac OS stores executables in the Mach-O file format. Mac OS X Mac OS X performs pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Object File
An object file is a file that contains machine code or bytecode, as well as other data and metadata, generated by a compiler or assembler from source code during the compilation or assembly process. The machine code that is generated is known as object code. The object code is usually relocatable, and not usually directly executable. There are various formats for object files, and the same machine code can be packaged in different object file formats. An object file may also work like a shared library. The metadata that object files may include can be used for linking or debugging; it includes information to resolve symbolic cross-references between different modules, relocation information, stack unwinding information, comments, program symbols, and debugging or profiling information. Other metadata may include the date and time of compilation, the compiler name and version, and other identifying information. The term "object program" dates from at least the 1950s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
External Variable
In the C programming language, and its predecessor B, an external variable is a variable defined outside any function block. On the other hand, a local (automatic) variable is a variable defined inside a function block. Definition, declaration and the extern keyword extrn In B, all variables must be declared, as one of auto, extrn, or implicitly as function arguments. An external variable is defined outside functions, has a lifetime of the whole program execution, and introduced to function by the mean of extrn declaration. Using the following code in the tutorial as an example: main( ) a 'hell'; b 'o, w'; c 'orld'; a, b, c are all external variables of the program defined outside functions, and introduced to the main function by extrn declarations. extern To understand how external variables relate to the extern keyword, it is necessary to know the difference between defining and declaring a variable. When a variable is ''defined'', the compiler allocates memory for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dynamic-link Library
A dynamic-link library (DLL) is a shared library in the Microsoft Windows or OS/2 operating system. A DLL can contain executable code (functions), data, and resources. A DLL file often has file extension .dll even though this is not required. The extension is sometimes used to describe the content of the file. For example, .ocx is a common extension for an ActiveX control and .drv for a legacy (16-bit) device driver. A DLL that contains only resources can be called a ''resource DLL''. Examples include an icon library, with common extension .icl, and a font library with common extensions .fon and .fot. The file format of a DLL is the same as for an executable (a.k.a. EXE). The main difference between a DLL file and an EXE file is that a DLL cannot be run directly since the operating system requires an entry point to start execution. Windows provides a utility program (RUNDLL.EXE/RUNDLL32.EXE) to execute a function exposed by a DLL. Since they have the same format, an EXE can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shared Library
In computing, a library is a collection of System resource, resources that can be leveraged during software development to implement a computer program. Commonly, a library consists of executable code such as compiled function (computer science), functions and Class (computer programming), classes, or a library can be a collection of source code. A resource library may contain data such as images and Text string, text. A library can be used by multiple, independent consumers (programs and other libraries). This differs from resources defined in a program which can usually only be used by that program. When a consumer uses a library resource, it gains the value of the library without having to implement it itself. Libraries encourage software reuse in a Modular programming, modular fashion. Libraries can use other libraries resulting in a hierarchy of libraries in a program. When writing code that uses a library, a programmer only needs to know how to use it not its internal d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loader (computing)
In computing, computer systems a loader is the part of an operating system that is responsible for loading computer program, programs and Library (computing), libraries. It is one of the essential stages in the process of starting a program, as it places programs into memory and prepares them for execution. Loading a program involves either memory-mapped file, memory-mapping or copying the contents of the executable, executable file containing the program instructions into memory, and then carrying out other required preparatory tasks to prepare the executable for running. Once loading is complete, the operating system starts the program by passing control to the loaded program code. All operating systems that support program loading have loaders, apart from highly specialized computer systems that only have a fixed set of specialized programs. Embedded systems typically do not have loaders, and instead, the code executes directly from ROM or similar. In order to load the operatin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Library (computing)
In computing, a library is a collection of System resource, resources that can be leveraged during software development to implement a computer program. Commonly, a library consists of executable code such as compiled function (computer science), functions and Class (computer programming), classes, or a library can be a collection of source code. A resource library may contain data such as images and Text string, text. A library can be used by multiple, independent consumers (programs and other libraries). This differs from resources defined in a program which can usually only be used by that program. When a consumer uses a library resource, it gains the value of the library without having to implement it itself. Libraries encourage software reuse in a Modular programming, modular fashion. Libraries can use other libraries resulting in a hierarchy of libraries in a program. When writing code that uses a library, a programmer only needs to know how to use it not its internal d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Static Build
A static build is a compiled version of a program which has been statically linked against libraries. Linking In computer science, linking means taking one or more objects generated by compilers and assembling them into a single executable program. The objects are program modules containing machine code and ''symbol'' definitions, which come in two varieties: *''Defined'' or ''exported'' symbols are functions or variables that are present in the module represented by the object, and which should be available for use by other modules. *''Undefined'' or ''imported'' symbols are functions or variables that are called or referenced by this object, but not internally defined. A linker program then resolves references to undefined symbols by finding out which other object defines a symbol in question, and replacing placeholders with the symbol's address. Linkers can take objects from a collection called a ''library''. The final program does not include the whole library, only those ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Static (keyword)
static is a reserved word in many programming languages to modify a declaration. The effect of the keyword varies depending on the details of the specific programming language, most commonly used to modify the lifetime (as a static variable) and visibility (depending on '' linkage''), or to specify a class member instead of an instance member in classes. Origin In the predecessors of C, including BCPL and B, there was already a concept of static storage., which meant a storage which is always in existence. However, In B, there wasn't a static keyword, but there was an extrn keyword to specify external storage (external to all functions and must be defined outside a function), which is always static, in contrast with auto keyword, which declared an variable with ''auto storage'' - one appears whenever the function is invoked, and disappears when the function is left. All variables must be declared, as one of auto, extrn, or implicitly as function arguments. C was developed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
External Linkage
In programming languages, particularly the compiled ones like C, C++, and D, linkage describes how names can or can not refer to the same entity throughout the whole program or one single translation unit. The static keyword is used in C to restrict the visibility of a function or variable to its translation unit. This is also valid in C++. (C++ 98/03 deprecated this usage in favor of anonymous namespaces, but is no longer deprecated in C++ 11.) Also, C++ implicitly treats any const namespace-scope variable as having internal linkage unless it is explicitly declared extern, unlike C. A name's linkage is related to, but distinct from, its scope. The scope of a name is the part of a translation unit where it is visible. For instance, a name with global scope (which is the same as file-scope in C and the same as the global namespace-scope in C++) is visible in any part of the file. Its scope will end at the end of the translation unit, whether or not that name has been given ext ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
