As far as I know, the compiler compiles the code by converting it to a language that a computer can understand which is the machine language and this is done before running the code.
So, does the compiler compile my code each time I write a character in the file?
And if so, does it check the whole code? Or just the line that updated.
An important part to this question is the type of programming language(PL) we are talking about. Generally speaking, I would categorize PL into 3 groups:
Traditional PLs. Ex: C, C++, Rust
The compiler compiles the code into machine language when you hit the "build" button or the "run" button.
It doesn't compile every time you change the code, but a code linter does continuously observe your code and check it for errors.
Another note, when you change part of the code and compile it, the compiler doesn't recompile everything. It usually only recompile the current assembly file (or module or whatever you call them).
It is also important to note that a lot of modern IDEs, compile when you save the files.
There is also the hot reload feature. It is a smart compiler feature that can swap certain parts of the code while it is running.
Interpreted PLs Ex: python, JS and PHP
Those languages never get compiled; Rather, they get interpreted or translated into native code on the fly and in-memory when you run them.
Those languages usually employee a cache to accelerate the subsequent code execution.
Intermediary Code PL. Ex: Kotlin, java, C#
Have 2 stages of compilation:
Build time compilation.
Just in time (run-time) compilation.
Build time compilation converts the code into intermediary language (IL) machine code, which is special to the run-time.
This code only understood by the run time like Java runtime or dot net runtime
The second compilation happens when the programs get installed or ran for the first time. This is called just in time compilation (JIT)
The run-time convert the code into native code specific to the run-time OS.
Related
How to directly run a c++ file present in read-only storage like CD-drive without making executable files using g++? There must be some arguments for that to work.
The process of a C/C++ program when you make one till you run it:
You write the program's source code.
The compiler comes in here and compiles the source code to object files.
Note: Remember that the program cannot be executed at this stage. It's only an object file. You'd know this if you have worked on bigger size programs, but if you haven't here is how it works. Remember using those header files in your programs? These header files just tell the compiler that there are some things that are not defined in your program. They are somewhere else. So your compile compiles the program to the object file leaving out things that have a prototype (which is in the header files).
This is a very important point. Here a program called 'linker' comes into play. What linker does is to take all the object files created by compiler and combines them into one. Say for example your compiler created a single object file. Now, you're using math library or anything from standard library. The compiler-linker package (often called only compiler) comes with object files for these standard library definitions. So, linker takes your object file and combines it with other object files from the package and then converts it to an executable file. This is the file that you can run. Nothing else is runnable directly.
To run source code the process is explained already, we have to use the g++. Now
What I understand from your question is that you want to know if a program can be run once it's compiled and linked properly (hence an executable has been generated). Answer to that would be yes.
Alternatively, may sound strange, there is an interpreter I know called Cling that can be of use to bypass the compilation of C++ program.
After all C++ is generally seen as a compiled language. However, any programming language can be implemented as a compiler or as an interpreter and Cling happens to be an interactive C++ interpreter based on LLVM and Clang.
Take a thorough look at this
I am trying to make some F# code conditional based on compile-time environment and can't find any OS-specific definitions that F# compiler would recognise. #if MONO doesn't work. Is there any way to detect OS at compile-time for F#?
I don't think there is any out-of-the box way of doing this. You will need to define your own symbol such as MONO and call the compiler with --define:MONO when building the Mono version.
That said, I would be a bit careful about this - there is no clear concept of "compiled for Mono" in F# and .NET. When you compile F# code, you always get a dll or exe that you can run anywhere and nothing prevents you from copying one build output and running it in another environment.
There is a standard way of detecting where the program is running at runtime using:
Type.GetType("Mono.Runtime") != null
You might have good reasons for wanting two separate builds, but it might be worth considering whether you can just make the appropriate choices at runtime (that probably does not work if you rely on some Windows-specific libraries such as WinForms charting).
I understand it is somehow making a connection so that a compiler when envokes connects a source code to whatever libraries that it needs to.
But what is going on a more technical level, or better put what do I need to know in order to confidentally compile code.
I'm working with C++ and MinGW, and have started to look into build files and stuff for Sublime Text 2 (Have learned mostly under unix, or Java + eclipse so far). But what I don't understand what is adding a compiler to your path do for you?
Do I need to add it for every folder I want to compile from? Or is it system wide? I'm really learning this stuff for the first time, we we're never showed how to set up development environments or even deploy code on other systems.
You probably mean include paths and library paths in the compiler:
include paths: where the compiler will look for headers; and
library paths: where the linker, invoked by the compiler, will look for binary libraries to finish building your project.
If that is the case, look here for a gentle explanation.
Basically, what is happening is that the compiler looks in certain places for symbols defined by the operating system and other libraries installed system-wide.
In addition to those paths, you need to tell the compiler where to find the symbols defined in your own project.
You may also mean something related to installing the compiler itself or configuring the editor to use it.
In that case, what is happening is that you need to tell the build system where to find the executable for the compiler.
Basically, what is probably happening is that your editor wants to know where the compiler is so that it can provide real time feedback on your code. Adding the compiler to the system path will usually, but not always, solve your problem.
In more detail:
A C++ build is a rather complex tool chain, involving determining dependencies, preprocessing, compiling, and linking. There are tools that automate that tool chain, and those tools are in turn wrapped into the functionality of modern IDEs like Eclipse, Visual C++, or Sublime Text 2. You many need to tell your editor where to find the tools it uses to provide you with those services.
I have recently edited a fellow student's data collection software to my specifications. The program works fine when I run within Visual Basic 6, however ideally I would like to compile the program into an .exe file so I can run it from any PC. However, when I select the option to turn it into an exe, I get the following error while its compiling:
Compile Error: Sub or Function not defined.
I was curious why my program will run from within Visual Basic, but can't compile into an exe. Any fixes/suggestions would be greatly appreciated!
You must just be running the app in the IDE by using Start (F5) - this does not do a full compile so won't catch all compile errors. I suggest you always use Start With Full Compile (Ctrl+F5) - then it will show you where the errors are.
You can create a custom control bar button to do the Start With Full Compile - saves typing CTRL+F5 all the time.
at the begining of every file, write "option explicit". This changes vb behavior from weak typed to strong typed.
What this means is that when you put a string into an integer, then the vb will tell you right away, or at least when you press "run". In a weak typed mode, the program will run until it encounters a fault, like "Sub or Function not defined" then crash.
When you compile into an "exe", vb needs to do extra sanity checks much like "option explicit" would do. This is why you don't see the problem while normal execution. It is still there, lurking, but you probably don't execute the problematic line.
It is very important that you use this keyword in every vb source file you have, otherwise you'll see problems like this all the time.
It allows you to run the program even though it won't compile due to the Compile On Demand feature the IDE supports. As noted in other posts you can CTRL-F5 to do a full compile, or you can go into Options --> General and turn off Compile On Demand...(saves a lot of CTRL-F5s)
We have a proprietry system that we develop scripting code in.
We currently do not have a developer environment (apart from Notepad++) and cannot debug or compile this code. We have to submit it to the vendor to insert the code into the test or live system.
The language is essentially C like and has the same syntax.
Basically we want a tool to be able to simply check the syntax of chunks of code we send to the vendor.
Does a tool exist that will do this for me?
You write code in a proprietary scripting language, so you require syntax checking because you cannot compile or debug the code onsite? I'd suggest getting a copy of the language reference (including the BNF if possible) from your vendor, get a compiler-compiler like Coco/R (http://www.ssw.uni-linz.ac.at/coco/), and build yourself a quick and dirty compiler that just validates the abstract syntax tree.
That is to say, yes, there are tools you can use, though perhaps they involve more work than what you may have hoped.
If it's really the same syntax as C you can use a C compiler. Usually there's a syntax check only option (/Zs for MSVC).
I'm not sure how many problems you'll run into since C compilers are pretty picky, and being "like C" is not the same as being C.
It does seem odd that you're being asked to develop code without having any capability to run or even compile it. Kind of like writing a book without being able to proof read it before publishing. I have a hard time getting even "Hello World" programs to compile & run without some sort of goof-up on the very first go.