Object code: Difference between revisions

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{{short description|Sequence of statements or instructions in a computer language}}

{{confuseddistinguish|Object-oriented programming}}

{{Use dmy dates|date=AugustApril 20222025}}

{{Program execution}}

In [[computing]], '''object code''' or '''object module''' is the product of aan [[assembler (computing)|assembler]] or [[compiler]].<ref>{{cite web|url=http://whatis.techtarget.com/definition/0,,sid9_gci211824,00.html|title=Compiler|publisher=TechTarget|quote=Traditionally, the output of the compilation has been called object code or sometimes an object module.|access-date=1 September 2011|archive-date=29 April 2012|archive-url=https://web.archive.org/web/20120429115801/http://whatis.techtarget.com/definition/0,,sid9_gci211824,00.html|url-status=dead}}</ref>

In a general sense, object code is a sequence of [[statement (computer science)|statements]] or instructions in a computer language,<ref>{{cite book |last1=Aho |first1=Alfred V. |author-link1=Alfred Aho |title=Compilers: principles, techniques, and tools |last2=Sethi |first2=Ravi |author-link2=RaviRavidassia Sethi|last3=Ullman |first3=Jeffrey DC. |author-link3=Jeffrey Ullman|title=Compilers: principles, techniques, and tools|series=Computer Science|year=1986|publisher=Mark S. Dalton |year=1986 |isbn=0-201-10194-7 |series=Computer Science |page=[https://archive.org/details/compilersprincip0000ahoa/page/704 704] |chapter=10 Code Optimization |chapter-url=https://archive.org/details/compilersprincip0000ahoa/page/704}}</ref> usually a [[machine code]] language (i.e., [[binary file|binary]]) or an intermediate language such as [[register transfer language]] (RTL). The term indicates that the code is the [[goal]] or result of the compiling process, with some early sources referring to source code as a "subject program".<ref>{{cite journal |last1=Luebbert |first1=William F. |last2=Collom jr. |first2=Percy |title=Signal Corps Research and Development on Automatic Programming of Digital Computers |journal=Communications of the ACM |date=February 1959 |volume=2 |issue=2 |pages=22–27 |url=https://doi.org/10.1145/368280.368293 |access-date=July 20, 2025}}</ref>

==Details==

[[Object file]]s can in turn be [[linker (computing)|linked]] to form an [[executable file]] or [[library (computing)|library file]]. In order to be used, object code must either be placed in an executable file, a library file, or an object file.

Object code is a portion of machine code that has not yet been linked into a complete program. It is the machine code for one particular library or module that will make up the completed product. It may also contain placeholders or offsets, not found in the machine code of a completed program, that the linker will use to connect everything together. Whereas machine code is binary code that can be executed directly by the CPU, object code has the jumps and inter-module references partially parametrized so that a linker can fill them in. An object file is assumed to begin at a specific ___location in memory, often zero. It contains information on instructions that reference memory, so that the linker can [[Relocation (computing)|relocate]] the code when combining multiple object files into a single program.

An [[assembler (computing)|assembler]] is used to convert [[assembly code]] into machine code (object code). A linker links several object (and library) files to generate an executable. Assemblers (and some compilers) can also assemble directly to machine code to produce executable files without the object intermediary step.<ref>{{cite web |last1=Fischer |first1=Charles N. |title=What do compilers produce? |url=https://pages.cs.wisc.edu/~fischer/cs536.s05/lectures/Lecture03.pdf |publisher=University of Wisconsin Madison |access-date=2 April 2024}}</ref>

==References==