What is O? What Opens a O? File Format List from WhatIs.com

File Extension

O File Format

Object file (Unix)

O is a file extension for an object file used with Unix and Linux systems. O stands for object. O files contain C or C++ source code to be compiled into an application. O files can be opened by GCC (GNU C and C++ Compiler) on Unix and Linux systems, and Microsoft Visual Studio on Windows systems.

The O file extension is also used for Atari object files and GCC object files

MIME type: application/x-object-file; application/x-object


Learn more about .O files:

See our C, C++ and C# Cheat Sheets.

Visit the C++ web page.

Read the C FAQ at ITKnowledgeExchange.com.

This was last updated in August 2010
Editorial Director Margaret Rouse

Ask a Question About OPowered by ITKnowledgeExchange.com

Get answers from your peers on your most technical challenges

Tech TalkComment

What made you want to look up O Object file (Unix)? Please tell us where you read or heard it (including the quote, if possible).



    Contribute to the conversation

    All fields are required. Comments will appear at the bottom of the article.