| title | description | ms.date | ms.topic | f1_keywords | helpviewer_keywords | ms.assetid | |||||||||
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ANSI C Conformance |
An overview of Microsoft C runtime naming conventions for ANSI C conformance. |
11/04/2016 |
conceptual |
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6be271bf-eecf-491a-a928-0ee2dd60e3b9 |
The naming convention for all Microsoft-specific identifiers in the run-time system (such as functions, macros, constants, variables, and type definitions) conforms to the ANSI/ISO C standards. In this documentation, any run-time function that follows the ANSI/ISO C standards is noted as being ANSI compatible. ANSI-conforming applications should only use these ANSI compatible functions.
The names of Microsoft-specific functions and global variables begin with a single underscore. These names can be overridden only locally, within the scope of your code. For example, when you include Microsoft run-time header files, you can still locally override the Microsoft-specific function named _open by declaring a local variable of the same name. However, you can't use this name for your own global function or global variable.
The names of Microsoft-specific macros and manifest constants begin with two underscores, or with a single leading underscore immediately followed by an uppercase letter. The scope of these identifiers is absolute. For example, you can't use the Microsoft-specific identifier _UPPER for this reason.