See also: Run time

In computer science, runtime or run time describes the operation of a computer program, the duration of its execution, from beginning to termination (compare compile time). Computer science (or computing science) is the study and the Science of the theoretical foundations of Information and Computation and their Computer programs (also software programs, or just programs) are instructions for a Computer. In Computer science, compile time refers to either the operations performed by a Compiler (the "compile-time operations" or Programming language The term runtime can also refer to a virtual machine to manage a program written in a computer language while it is running. In Computer science, a virtual machine (VM is a Software implementation of a machine (computer that executes programs like a real machine run time is sometimes used to mean runtime library, a library of basic code that is used by a particular compiler but when used in this fashion, runtime library is more accurate. In Computer programming, a runtime library is a special Program library used by a Compiler, to implement functions built into a Programming language A compiler is a Computer program (or set of programs that translates text written in a computer language (the source language) into another

A runtime environment is a virtual machine state which provides software services for processes or programs while a computer is running. It may pertain to the operating system itself, or the software that runs beneath it. The primary purpose is to accomplish the objective of "platform independent" programming.

Runtime activities include loading and linking of the classes needed to execute a program, optional machine code generation and dynamic optimization of the program, and actual program execution.

For example, a program written in Java would receive services from the Java Runtime Environment by issuing commands from which the expected result is returned by the Java software. A Java Virtual Machine ( JVM) is a set of computer software programs and data structures which use a Virtual machine By providing these services, the Java software is considered the runtime environment of the program. Both the program and the Java software combined request services from the operating system. The operating system kernel provides services for itself and all processes and software running under its control. The Operating System may be considered as providing a runtime environment for itself.

Contents 1 Implementation details 2 Application errors — exceptions 3 See also 4 References

Implementation details

In most cases, the operating system handles loading the program with a piece of code called the loader, doing basic memory setup and linking the program with any dynamically linked libraries it references. In Computing, a loader is the part of an operating system that is responsible for loading programs from executables (i Computer data storage, often called storage or memory, refers to Computer components devices and recording media that retain digital In some cases a language or implementation will have these tasks done by the language runtime instead, though this is unusual in mainstream languages on common consumer operating systems.

Some program debugging can only be performed (or are more efficient or accurate) when performed at runtime. Logical errors and array bounds checking are examples. In Mathematics, Computing, Linguistics and related subjects an algorithm is a sequence of finite instructions often used for Calculation In Computer science an array is a Data structure consisting of a group of elements that are accessed by indexing. 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 pre-release testing. A software bug (or just “bug” is an error flaw mistake Failure, fault or “undocumented feature” in a Computer program that prevents it In this case, the end user may encounter a runtime error message.

Early runtime libraries such as that of Fortran provided such features as mathematical operations. Fortran (previously FORTRAN) is a general-purpose, procedural, imperative Programming language that is especially suited to Other languages add more sophisticated memory garbage collection, often in association with support for objects. In Computer science, garbage collection ( GC) is a form of automatic Memory management.

More recent languages tend to have considerably larger runtimes with considerably more functionality. Many object oriented languages also include a system known as the "dispatcher" and "classloader". The Java Classloader is a part of the Java Runtime Environment that dynamically loads Java classes into the Java Virtual Machine. The Java Virtual Machine (JVM) is an example of such a runtime: It also interprets or compiles the portable binary Java programs (bytecode) at runtime. A Java Virtual Machine ( JVM) is a set of computer software programs and data structures which use a Virtual machine Bytecode is a term which has been used to denote various forms of Instruction sets designed for efficient execution by a software interpreter as well as being suitable The .NET framework is another example of a runtime library.

Application errors — exceptions

Exception handling is one language feature designed to handle runtime errors, providing a structured way to catch completely unexpected situations as well as predictable errors or unusual results without the amount of inline error checking required of languages without it. Exception handling is a programming language construct or computer hardware mechanism designed to handle the occurrence of a condition that changes the normal flow of execution More recent advancements in runtime engines enable Automated Exception Handling which provides 'root-cause' debug information for every exception of interest and is implemented independent of the source code, by attaching a special software product to the runtime engine. Automated Exception Handling is a Computing term referring to the computerized handling of errors

See also

• Compile time and compiling
• Runtime Type Information
• Binding (computer science)
• Interpreter (computing)
• Run-time system

References

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