Runtime library

The term runtime library (English runtime library ) is used in computer science. He refers to a special program library, a collection of software functions that is used to realize the built in a programming language functions at the time of execution of the program (term ) within a computer program. These often include, for example, functions for input and output, memory management and mathematical functions.

If the source code of a computer program is translated by a compiler in the target language, as it would lead to hardly portable magnification of the program code when generated for each statement in the program and each call to a built-in function in each case at the corresponding point of the full program code in the target language would have to be. Instead, the compiler often generates calls to compiler-specific auxiliary functions, which does not usually available to the application programmer directly available and their implementations are in the runtime library. The runtime library is at the discretion of the compiler manufacturer also often contain parts of the standard library of the respective compiler or be combined with this.

Depending on programming and implementation may include the runtime library also run-time checks, such as boundaries of arrays or dynamic type checking, exception handling, and other features for troubleshooting (debugging).

The runtime library implements many functions normally, with access to the operating system. Many programming languages ​​have built-in functions that need not necessarily be implemented in the compiler, but can also be implemented in the runtime library. The boundary between the compiler and runtime library is therefore in the discretion of the compiler manufacturer. For these reasons, the runtime library is always compiler-specific and platform-specific.

It should not be confused the concept of run-time library with a normal program library, as created by an application programmer or provided to a third party, or a dynamic library, what is referred to one of the linked runtime library program. For example, the C programming language required only a minimal runtime library, but writes the C standard library functions before, the need to bring any C implementation.

Some modern programming languages ​​such as Java use instead a simple runtime library a more complex runtime environment.

• Library (programming)
• Compiler