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ANSI Standard Issues

Divergence from the ANSI C Standard

The mikroC PRO for AVR diverges from the ANSI C standard in a few areas. Some of these modifications are improvements intended to facilitate AVR programming, while others are the result of AVR hardware limitations.

• Case Sensitivity. Check identifiers
• The mikroC PRO for AVR treats identifiers declared with the const qualifier as “true constants” (C++ style). This allows using const objects in places where ANSI C expects a constant expression. If aiming at portability, use the traditional preprocessor defined constants. See Type Qualifiers and Constants.
• The mikroC PRO for AVR allows C++ style single–line comments using two adjacent slashes (//). The comment can start at any position and extends until the next new line. See Comments.
• A number of standard C libraries (ctype, math, stdlib, string) have been implemented; check the individual functions for divergence.
• The mikroC PRO for AVR does not provide automatic initialization for objects. Uninitialized globals and objects with static duration will take random values from memory.
• Anonymous unions and structures are now supported.

C Language Extensions

mikroC PRO for AVR has additional set of keywords that do not belong to the ANSI standard C language keywords:

• code
• data
• io
• rx
• sfr
• near
• far
• at
• sbit
• bit
• iv

Implementation-defined Behavior

Certain sections of the ANSI standard have implementation-defined behavior. This means that the exact behavior of some C code can vary from compiler to compiler. This Help contains the sections describing how the mikroC PRO for AVR compiler behaves in such situations.

The most notable specifics include:

• Storage Classes
• Bit Fields

Related topics: Keywords, AVR Specific