Opening an O File

The O file type is primarily associated with Visual Studio.

O	File extension: O
	File type:	compiled object

What is an O file?

O files mostly belong to Visual Studio by Microsoft. O is the filename extension of an object generated from source code written in various compiled programming languages such as C and C++. If for example, a C++ project contains source files named "main.cpp" and "user.cpp", a compiler such as GCC must compile these files to "main.o" and "user.o" before the linker bundles both files into an executable program. An O file developed within in a Windows environment is usually compiled to an EXE file while those created in Unix-based environments are saved in Executable and Linkable Format. An object generated in other environments may be saved in other formats.

How to open an O file

You need a suitable software like Visual Studio to open an O file. Without proper software you will receive a Windows message "How do you want to open this file?" or "Windows cannot open this file" or a similar Mac/iPhone/Android alert. If you cannot open your O file correctly, try to right-click or long-press the file. Then click "Open with" and choose an application. You can also display a O file directly in the browser:. Just drag the file onto this browser window and drop it.

Online O Text Viewer

Choose your .o file to analyze

or drag and drop it here

Online File Viewer

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Programs that open and convert O files:

Visual Studio by Microsoft
See the previous paragraphs to learn more about the main application. O files are often referred to as Visual Studio developers because this type of file is primarily created or used by this software.
7-zip (compressed data) by Igor Pavlov
7-zip is an archive file compression program. It can be used to decompress and extract the contents of an O file saved in ZIP archive format. This file format is classified as Compressed.
Acrobat (document) by Adobe
Acrobat is a cross-platform program for creating, signing, and reading documents saved in Portable Document Format (PDF). It can open an O file saved in PDF format. This file format is classified as Data. Related links: PDF
Arm Compiler (compiled object) by Arm
Arm Compiler is a cross-platform program for compiling C, C++, and Assembly source code for embedded systems. An object compiled from source written in any of these languages is saved in an O file. This file format is classified as Developer. Related links: Arm Compiler 6
Free Pascal (compiled object) by FPC Development Team
Free Pascal is an open source compiler for programs written in Pascal programming language. A compiled object created by Linux and DOS editions of Free Pascal is saved in an O file. This file format is classified as Developer.
GCC (compiled object) by Free Software Foundation
GCC (short for GNU Compiler Collection) is a command-line software suite featuring compilers for C, C++, Ada, Fortran etc. Source code compiled with GCC on a UNIX-based system is saved in an O, OBJ, or OUT file. This file format is classified as Developer.
Origin (data) by OriginLab
Origin is a scientific data analysis and data visualization software used for scientific research. It uses an O file to store data. This file format is classified as Data.
Xcode (compiled object) by Apple
Xcode is an integrated development environment for building cross-platform applications. It uses an O file (usually saved in Mach-O binary format) to store the compiled object of an iOS application written in C. This file format is classified as Developer.

O file format details:

If you can determine the file format, the associated program can also be determined. Each file format has a unique extension and almost always a unique signature. For example, Microsoft Word documents have the extension .docx and the signature (usually the first 3 characters in this file) PK. However, different programs can use the same file extension. Furthermore, a file extension can be renamed incorrectly and double-clicking on it will then display an error when it is opened. So a detailed analysis of a file is vital in order to determine the format and the associated program. In the following you will find our evaluation of the O files:

O is a very commonly used file extension and includes different formats for different programs. The two most popular formats are as follows:

45% of all O files are ELF Executable and Linkable format files, which are based on the ELF file format. ELF is the abbreviation for Executable and Linkable Format and is the standard binary format on Linux and Unix. The contents of these files cannot be read by a human; only a computer program can interpret the data. The file size is in the range of 1 KB to 150 KB. The file type was created 10 years ago, but is still used today. Some examples of file names are Main.o. Files like these have the following tags: hello, audio, supplied, given, assignment, problem, program, driver, serial and check.
15% of all O files are Intel 80386 Common Object File Format object / library files. They consist of illegible, cryptic characters. A typical file size is 3 KB. The keywords .text, .bss, 0`.data and .rdata are typical for these files. Examples of file names are Main.o. Files like these have the following tags: system, management, library, array, game, funciones and world.

The remaining 40% of all O files are files with no common format, the following 16 formats exist: PDF, EXE, ZIP, NQVT, ACS, ORC, COMMAND, MjM and head. They are often associated with project, ftest, client, swarm, data or tests. If you want to find out which format your O file belongs to, just click on the button "Choose your .o file to analyze".

Technical Data for O File Extension

File classification:

Developer

Related files:

elf, c, obj, a, problem1_given, cpp, so, exe, 15o, pas, init_sat, zip, h, dwarf, out, pbi, d, o_, solitaire, sou, lib, mdp, res

Mime type:

application/octet-stream, application/x-object, application/x-coff

The following listing is compiled from the database produced by the 'Associate This!' program, selected data from the main FILExt database and file extension information submitted by users.

ProgramID: Shareaza.Collection
EXEFile: D:\Shareaza\Shareaza.exe %1

an o compiled object is a special file format by Microsoft and should only be edited and saved with the appropriate software.

How to solve problems with O files

Associate the O file extension with the correct application.
Update your software that should actually open compiled objects. Because only the current version supports the latest O file format. Search, therefore, e.g. on the Microsoft manufacturer website after an available Visual Studio update.
To make sure that your O file is not corrupted or virus-infected, get the file again and scan it with Google's virustotal.com.
Click here to open your .O file online - secure, fast, and no downloads needed.