When is c compiled

The whole point here is that the language itself is not compiled nor interpreted; it is just a textual standard. The implementation details of turning that text into machine instructions is where the compilation or interpretation choice is made. It's typically compiled, although there is of course nothing preventing people from implementing interpreters.

There are languages which are designed to make compilation easy , by giving the user only features that directly map to machine instructions, such as arithmetic, pointer manipulation, function calls and indirect function calls which give you virtual dispatch.

Interpretation of these is generally also easy, but particularly poor performance. C is one of these. Other languages are designed for interpretation. These often have dynamic typing, lazy dispatch, dynamic not lexical scope of closures, reflection, dynamic codegen, and other features that make compilation incredibly difficult.

Of course difficult is not the same as impossible, and some of these languages do end up with compilers as a result of Herculean efforts. Stack Overflow for Teams — Collaborate and share knowledge with a private group.

Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Asked 7 years, 11 months ago. Active 1 year, 5 months ago. Viewed 17k times. Improve this question. Adrian Mole Hanoch Hanoch 1 1 gold badge 3 3 silver badges 10 10 bronze badges.

Read this answer: stackoverflow. It's usually compiled into assembly. Although that doesn't mean no interpreter exists in fact, there does. Languages are not "compiled" or "interpreted".

Their implementations might be located somewhare on "compiled-interpreted" spectrum. Is there any reason for the downvotes? A compiler is a program. A compiler takes the recipe code for a new program written in a high level language and transforms this Code into a new language Machine Language that can be understood by the computer itself.

This "machine language" is difficult to impossible for humans to read and understand much less debug and maintain , thus the need for "high level languages" such as C. The compiler also ensures that your program is TYPE correct. For example, you are not allowed to assign a string to an integer variable! The compiler also ensures that your program is syntactically correct.

This command can be written at the Linux command window, or can be typed in using emac's compile command. A bootloader has different requirements, so its file format might be different. But the idea is the same: binary code is always a payload in a larger file format, which includes at a minimum a sanity check to ensure that it's written in the correct instruction set.

C compilers and assemblers are typically configured to produce static library files. For embedded applications, you're more likely to find a compiler which produces something like a raw memory image with instructions beginning at address zero. Otherwise, you can write a linker which converts the output of the C compiler into whatever else you want. As I understand it, a chipset CPU, etc. The instructions will be things like 'store this value to this register', 'move this value', or 'compare these two values'.

These instructions are often expressed in short human-grokable alphabetic codes assembly language, or assembler which are mapped to the numbers that the chipset understands - those numbers are presented to the chip in binary machine code.

Those codes are the lowest level that the software gets down to. Going deeper than that gets into the architecture of the actual chip, which is something I haven't gotten involved in.

The executable files PE format on windows cannot be used to boot the computer because the PE loader is not in memory. The way bootstrapping works is that the master boot record on the disk contains a blob of a few hundred bytes of code.

This is raw machine code that, like the MBR loader, is loaded into memory cold and executed. OS kernel, as well as bootloader, also written in C, so no problems here. NET , which makes it cross-OS and cross-platform, but requires local interpreter or translator to run. Stack Overflow for Teams — Collaborate and share knowledge with a private group.

Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. What do C and Assembler actually compile to? Asked 11 years, 9 months ago. Active 6 months ago. Viewed 25k times.

Improve this question. The bootloader is just machine code without the binary headers and other stuff that the OS uses when it loads a binary in memory. Simply put, they can get "packaged" differently. Unfortunately, I do not have a copy it. Geoffey Schildt's book has strong claims to be the worst technical book ever written - it is riddled with errors and untruths. Before progressing further as a developer, you should have clear understanding of the terms: machine code , binary code , assembly language , executable code and microcode.

Many people treat these as the same meaning, but they are different, especially with Embedded Systems Programming. Note also that gcc doesn't compile to machinecode. It compiles to assembler. AS then translates the assembler to machinecode.

However most compilers do directly output machinecode — Marco van de Voort. Show 6 more comments. Active Oldest Votes. The key parts are: Code and data appear in named "sections". Improve this answer. Norman Ramsey Norman Ramsey k 57 57 gold badges silver badges bronze badges. Most C compilers compile directly to relocatable machine code.

It is faster to skip the slow textual step. Some like bit compilers capable of. COM files can generate non-relocatable code directly. One could argue though that in directly machinecode generating compilers, the assembler is a relative separate standing part. Relocatable code is not a requirement of C, and many platforms don't use it. Is there any script for your course available online?

Lothar my course is online at cs. For past years, see my home page. For obvious reasons the answers are not online. As discussed under your answer on a duplicate Do programming language compilers first translate to assembly or directly to machine code?

See also Does a compiler always produce an assembly code? Add a comment. Let's take a C program. When you run gcc , clang , or 'cl' on the c program, it will go through these stages: Preprocessor include, ifdef, trigraph analysis, encoding translations, comment management, macros Lexical analysis producing tokens and lexical errors.

Syntactical analysis producing a parse tree and syntactical errors. Often an SSA. Optimization of the program logic, including constant propagation, inlining, hoisting invariants out of loops, auto-vectorization, and many many other things.

Most of the code for a widely-used modern compiler is optimization passes. Linking of the assembly into whatever static libraries are needed, as well as relocating it if needed.

Hmm, the Dragon book is mostly about parsing. I'd recommend "Linkers and Loaders" by Levine, iecc. Linkers and loaders is also a good book.

Actually, in the "logical" order, lexical analysis occurs before preprocessing, because the preprocessor operates on a stream of tokens. That's how it is defined in the C standard, and that is also how it happens in modern versions of gcc when the preprocessor was rewritten and turned into a lexing library.

Thomas: Interesting! I am out of date — Paul Nathan.