GENERAL: Inline Functions in C

Information in this article applies to:

• C166 all Versions
• C251 all Versions
• C51 all Versions
• ARMCC all Versions

QUESTION

Does the Keil C Compiler support inline C functions?

ANSWER

This depends on the toolset. Function inlining with the '__inline' keyword was standardized with C99 and C++.

• C51 and C251: These compilers do not support the __inline keyword.
• C166: Function inlining was added to the C166 compiler with version 4.25 in February 2003. Please see the chapter Inline Functions in the C166 manual for more details.
• ARMCC: Function inlining is supported in every version. Please see the chapter Inline functions in the ARMCC user manual for more details.

With all tools, you may of course use the #define preprocessor directive to create a (multiline-) macro that expands inline.

Last Reviewed: Thursday, February 25, 2021