What is runtime

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I have heard about things like  quot C Runtime quot    quot Visual C   2008 Runtime quot    quot  NET Common Language Runtime quot   etc   What is  quot runtime quot  exactly  What is it made of  How does it interact with my code  Or maybe more precisely  how is my code controlled by it   When coding assembly language on Linux  I could use the INT instruction to make the system call  So  is the runtime nothing but a bunch of pre-fabricated functions that wrap the low level function into more abstract and high level functions  But doesn t this seem more like the definition for the library  not for the runtime  Are  quot runtime quot  and  quot runtime library quot  two different things  ADD 1 These days  I am thinking maybe Runtime has something in common with the so called Virtual Machine  such as JVM  Here s the quotation that leads to such thought   This compilation process is sufficiently complex to be broken into several layers of abstraction  and these usually involve three translators  a compiler  a virtual machine implementation  and an assembler   --- The Elements of Computing Systems  Introduction  The Road Down To Hardware Land   ADD 2 The book Expert C Programming  Deep C Secrets  Chapter 6 Runtime Data Structures is an useful reference to this question  ADD 3 - 7 31 AM 2 28 2021 Here s some of my perspective after getting some knowledge about processor design  The whole computer thing is just multiple levels of abstraction  It goes from elementary transistors all the way up to the running program  For any level N of abstraction  its runtime is the immediate level N-1 of abstraction that goes below it  And it is God that give us the level 0 of abstraction

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Run time is the instance where you don t know about of what type of objects creates during its execution  objects creation are based on certain condition or some computation work   In contradict  compile time is the instance where required objects are defined by you before its executions

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I m not crazy about the other answers here  they re too vague and abstract for me  I think more in stories  Here s my attempt at a better answer  a BASIC example Let s say it s 1985 and you write a short BASIC program on an Apple II    10 PRINT  quot HELLO WORLD  quot    20 GOTO 10  So far  your program is just source code  It s not running  and we would say there is no  quot runtime quot  involved with it  But now I run it    RUN  How is it actually running  How does it know how to send the string parameter from PRINT to the physical screen  I certainly didn t provide any system information in my code  and PRINT itself doesn t know anything about my system  Instead  RUN is actually a program itself -- its code tells it how to parse my code  how to execute it  and how to send any relevant requests to the computer s operating system  The RUN program provides the  quot runtime quot  environment that acts as a layer between the operating system and my source code  The operating system itself acts as part of this  quot runtime quot   but we usually don t mean to include it when we talk about a  quot runtime quot  like the RUN program  Types of compilation and runtime Compiled binary languages In some languages  your source code must be compiled before it can be run  Some languages compile your code into machine language -- it can be run by your operating system directly  This compiled code is often called  quot binary quot   even though every other kind of file is also in binary     In this case  there is still a minimal  quot runtime quot  involved -- but that runtime is provided by the operating system itself  The compile step means that many statements that would cause your program to crash are detected before the code is ever run  C is one such language  when you run a C program  it s totally able to send illegal requests to the operating system  like   quot give me control of all of the memory on the computer  and erase it all quot    If an illegal request is hit  usually the OS will just kill your program and not tell you why  and dump the contents of that program s memory at the time it was killed to a  dump file that s pretty hard to make sense of  But sometimes your code has a command that is a very bad idea  but the OS doesn t consider it illegal  like  quot erase a random bit of memory this program is using quot   that can cause super weird problems that are hard to get to the bottom of  Bytecode languages Other languages compile your code into a language that the operating system can t read directly  but a specific runtime program can read your compiled code  This compiled code is often called  quot bytecode quot   The more elaborate this runtime program is  the more extra stuff it can do on the side that your code did not include  even in the libraries you use  -- for instance  the Java runtime environment   quot JRE quot   can keep track of memory assignments that are no longer needed  and tell the operating system it s safe to reuse that memory for something else  and it can catch situations where your code would try to send an illegal request to the operating system  and instead exit with a readable error  All of this overhead makes them slower than compiled binary languages  but it makes the runtime powerful and flexible  in some cases  it can even pull in other code after it starts running  without having to start over  The compile step means that many statements that would cause your program to crash are detected before the code is ever run  and the powerful runtime can keep your code from doing stupid things  e g   you can t  quot erase a random bit of memory this program is using quot    Scripting languages Still other languages don t precompile your code at all  the runtime does all of the work of reading your code line by line  interpreting it and executing it  This makes them even slower than  quot bytecode quot  languages  but also even more flexible  in some cases  you can even fiddle with your source code as it runs  Though it also means that you can have a totally illegal statement in your code  and it could sit there in your production code without drawing attention  until one day it is run and causes a crash  These are generally called  quot scripting quot  languages  they include Javascript  Python  Perl  and PHP  Some of these provide cases where you can choose to compile the code to improve its speed  e g   Javascript s WebAssembly project  and Python s trans-compilation to C code   So Javascript can allow users on a website to see the exact code that is running  since their browser is providing the runtime  This flexibility also allows for innovations in runtime environments  like node js  which is both a code library and a runtime environment that can run your Javascript code as a server  which involves behaving very differently than if you tried to run the same code on a browser

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In my understanding runtime is exactly what it means - the time when the program is run  You can say something happens at runtime   run time or at compile time   I think runtime and runtime library should be  if they aren t  two separate things   C runtime  doesn t seem right to me  I call it  C runtime library    Answers to your other questions  I think the term runtime can be extended to include also the environment and the context of the program when it is run  so    it consists of everything that can be called  environment  during the time when the program is run  for example other processes  state of the operating system and used libraries  state of other processes  etc it doesn t interact with your code in a general sense  it just defines in what circumstances your code works  what is available to it during execution    This answer is to some extend just my opinion  not a fact or definition

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I found that the following folder structure makes a very insightful context for understanding what runtime is     You can see that there is the  source   there is the  SDK  or  Software Development Kit  and then there is the Runtime  eg  the stuff that gets run - at runtime  It s contents are like     The win32 zip contains  exe -s and  dll -s   So eg  the C runtime would be the files like this -- C runtime libraries   so-s or  dll -s -- you run at runtime  made special by their  or their contents  or purposes   inclusion in the definition of the C language  on  paper    then implemented by your C implementation of choice  And then you get the runtime of that implementation  to use it and to build upon it    That is  with a little polarisation  the runnable files that the users of your new C-based program will need  As a developer of a C-based program  so do you  but you need the C compiler and the C library headers  too  the users don t need those

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These sections of the MSDN documentation deal with most of your questions  http   msdn microsoft com en-us library 8bs2ecf4 VS 71  aspx  I hope this helps   Thanks  Damian

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Runtime is somewhat opposite to design-time and compile-time link-time  Historically it comes from slow mainframe environment where machine-time was expensive

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Runtime basically means when program interacts with the hardware and operating system of a machine  C does not have it s own runtime but instead  it requests runtime from an operating system  which is basically a part of ram  to execute itself

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Runtime describes software instructions that are executed while your program is running  especially those instructions that you did not write explicitly  but are necessary for the proper execution of your code   Low-level languages like C have very small  if any  runtime  More complex languages like Objective-C  which allows for dynamic message passing  have a much more extensive runtime   You are correct that runtime code is library code  but library code is a more general term  describing the code produced by any library  Runtime code is specifically the code required to implement the features of the language itself

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If my understanding from reading the above answers is correct  Runtime is basically  background processes  such as garbage collection  memory-allocation  basically any processes that are invoked indirectly  by the libraries   frameworks that your code is written in  and specifically those processes that occur after compilation  while the application is running

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The runtime or execution environment is the part of a language implementation which executes code and is present at run-time  the compile-time part of the implementation is called the translation environment in the C standard   Examples    the Java runtime consists of the virtual machine and the standard library a common C runtime consists of the loader  which is part of the operating system  and the runtime library  which implements the parts of the C language which are not built into the executable by the compiler  in hosted environments  this includes most parts of the standard library

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a runtime could denote the current phase of program life  runtime   compile time   load time   link time  or it could mean a runtime library  which form the basic low level actions that interface with the execution environment  or it could mean a runtime system  which is the same as an execution environment   in the case of C programs  the runtime is the code that sets up the stack  the heap etc  which a requirement expected by the C environment  it essentially sets up the environment that is promised by the language   it could have a runtime library component  crt0 lib or something like that in case of C

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As per Wikipedia  runtime library run-time system      In computer programming  a runtime library is a special program library used by a compiler  to implement functions built into a programming language  during the runtime  execution  of a computer program  This often includes functions for input and output  or for memory management         A run-time system  also called runtime system or just runtime  is software designed to support the execution of computer programs written in some computer language  The run-time system contains implementations of basic low-level commands and may also implement higher-level commands and may support type checking  debugging  and even code generation and optimization    Some services of the run-time system are accessible to the programmer through an application programming interface  but other services  such as task scheduling and resource management  may be inaccessible      Re  your edit   runtime  and  runtime library  are two different names for the same thing

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Runtime is a general term that refers to any library  framework  or platform that your code runs on   The C and C   runtimes are collections of functions   The  NET runtime contains an intermediate language interpreter  a garbage collector  and more

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Matt Ball answered it correctly  I would say about it with examples   Consider running a program compiled in Turbo-Borland C C    version 3 1 from the year 1991  compiler and let it run under a 32-bit version of windows like Win 98 2000 etc   It s a 16-bit compiler  And you will see all your programs have 16-bit pointers  Why is it so when your OS is 32bit  Because your compiler has set up the execution environment of 16 bit and the 32-bit version of OS supported it   What is commonly called as JRE  Java Runtime Environment  provides a Java program with all the resources it may need to execute   Actually  runtime environment is brain product of idea of Virtual Machines  A virtual machine implements the raw interface between hardware and what a program may need to execute  The runtime environment adopts these interfaces and presents them for the use of the programmer  A compiler developer would need these facilities to provide an execution environment for its programs

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Run time exactly where your code comes into life and you can see lot of important thing your code do   Runtime has a responsibility of allocating memory   freeing memory   using operating system s sub system like  File Services  IO Services   Network Services etc    Your code will be called  WORKING IN THEORY  until you practically run your code  and Runtime is a friend which helps in achiving this

[terminology] What is "runtime"?

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