A runtime library is a

library A library is a collection of Book, books, and possibly other Document, materials and Media (communication), media, that is accessible for use by its members and members of allied institutions. Libraries provide physical (hard copies) or electron ...

that provides access to the

runtime environment In computer programming, a runtime system or runtime environment is a sub-system that exists in the computer where a program is created, as well as in the computers where the program is intended to be run. The name comes from the compile time ...

that is available to a

computer program A computer program is a sequence or set of instructions in a programming language for a computer to Execution (computing), execute. It is one component of software, which also includes software documentation, documentation and other intangibl ...

tailored to the host platform. A runtime environment implements the execution model as required for a development environment such as a particular

programming language A programming language is a system of notation for writing computer programs. Programming languages are described in terms of their Syntax (programming languages), syntax (form) and semantics (computer science), semantics (meaning), usually def ...

. A runtime library may provide basic program facilities such as for

memory management Memory management (also dynamic memory management, dynamic storage allocation, or dynamic memory allocation) is a form of Resource management (computing), resource management applied to computer memory. The essential requirement of memory manag ...

and

exception handling In computing and computer programming, exception handling is the process of responding to the occurrence of ''exceptions'' – anomalous or exceptional conditions requiring special processing – during the execution of a program. In general, an ...

. A runtime library is an artifact of the design of the

toolchain A toolchain is a set of software development tools used to build and otherwise develop software. Often, the tools are executed sequentially and form a pipeline such that the output of one tool is the input for the next. Sometimes the term is us ...

used to build the program not inherently required by the host

operating system An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...

or the

in which the program is written. The toolset is designed to abstract aspects of the host platform often to simplify

tool A tool is an Physical object, object that can extend an individual's ability to modify features of the surrounding environment or help them accomplish a particular task. Although many Tool use by animals, animals use simple tools, only human bei ...

development. The toolchain builds a program to depend on a runtime library and to use it while the program is running at program run-time. The runtime library may directly implement runtime behavior, but often it is a thin wrapper on top of operating system facilities. For example, some language features that can be performed only (or are more efficient or accurate) at runtime are implemented in the runtime environment and may be invoked via the runtime library API, e.g. some logic errors, array

bounds checking In computer programming, bounds checking is any method of detecting whether a variable is within some bounds before it is used. It is usually used to ensure that a number fits into a given type (range checking), or that a variable being used as ...

, dynamic type checking, exception handling, and possibly debugging functionality. For this reason, some programming bugs are not discovered until the program is tested in a "live" environment with real data, despite sophisticated compile-time checking and testing performed during development. As another example, a runtime library may contain code of built-in low-level operations too complicated for their inlining during compilation, such as implementations of arithmetic operations not directly supported by the targeted CPU, or various miscellaneous compiler-specific operations and directives. The runtime library is often confused with the language

standard library In computer programming, a standard library is the library (computing), library made available across Programming language implementation, implementations of a programming language. Often, a standard library is specified by its associated program ...

which implements functionality as defined by a language. A standard library could be implemented in a platform-specific way or it could leverage a runtime library to be platform independent. For example, the

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 Electrote ...

is relatively large while the platform-specific runtime library (commonly called crt0) is relatively small which eases supporting multiple platforms.

Examples

glibc The GNU C Library, commonly known as glibc, is the GNU Project implementation of the C standard library. It provides a wrapper around the system calls of the Linux kernel and other kernels for application use. Despite its name, it now also dir ...

* msvcrt

References

{{Reflist

External links

What is the C runtime library?
(

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) Computer libraries Run-time systems

Examples

See also

References

External links