C99 Support in Intel® C++ Compiler

By Jennifer L Jiang,

Published:08/26/2014   Last Updated:09/11/2017

The following C99 features are supported by Intel® C++ Compiler 12.0 or newer.

The option to turn on C99 support:  

  • /Qstd=c99 on Windows*
  • -std=c99 on Linux* and macOS*
  • The default is C89 instead

The following C99 features are supported:

  • restricted pointers (restrict keyword)
  • variable-length Arrays
  • flexible array members
  • complex number support (_Complex keyword)
  • hexadecimal floating-point constants
  • compound literals
  • designated initializers
  • mixed declarations and code
  • macros with a variable number of arguments
  • inline functions (inline keyword)
  • boolean type (_Bool keyword)

See C11 Features Supported by Intel(R) C++ compiler for supported C11 (C1x) features.

See C++0x Features Supported by Intel® C++ Compiler for supported C++0x features.

Product and Performance Information


Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice.

Notice revision #20110804