CODEWITHSUNDEEP
c++compilation
ICanKindOfCode
ICanKindOfCode

Reputation: 1120

If C++ compiles to machine code, why do we need to install a 'runtime'?

At the end of the compilation process, the program is in a .exe file in machine code. So shouldn't the machine be able to run it without having to install something like MS Visual Studio C++? Basically, I am making a program with mingw and want to share it with someone else. I do not understand why I can not just send them the .exe file. Clarification will be appreciated.

Upvotes: 7

Views: 1250

Answers (2)

Jesper Juhl
Jesper Juhl

Reputation: 31465

Your program likely calls many functions from the standard library that you didn't write yourself. You need the runtime libraries for that. Your code probably also needs code run before main to setup the basic environment that's expected for a C++ program - the runtime libs do that for you. Also after main ends, various cleanup needs to happen according to the standard (and your program probably also depends on this) and the compilers runtime libraries take care of this.

Your code does not exist in a vacuum (it can, but then it's no longer a standard hosted C++ program). It depends on and relies on the standard runtime libs to provide the environment the C++ standard says you can expect.

Upvotes: 6

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726569

C++ compiles your code to machine code. If your program is self-contained, that is all you need. However, more complex running programs often relies on additional compiled code, which is made available to your program through a library.

Generally, libraries come in two "flavors" - static and dynamic. Static libraries are "baked into" your compiled code. This is not ideal, because multiple programs include identical code, leading to code duplication. Dynamic libraries, on the other hand, are shared among all programs using them, leading to more efficient use of space.

Installing runtime adds dynamic libraries for use by all programs compiled with C++.

Upvotes: 14

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