Question

What features of C++ should be avoided in embedded systems?

Please classify the answer by reason such as:

• memory usage
• code size
• speed
• portability

EDIT: Lets’ use an ARM7TDMI with 64k ram as a target to control the scope of the answers.

Answer 1

RTTI and Exception Handling:

• Increases code-size
• Decreases performance
• Can often be replaced by cheaper mechanisms or a better software-design.

Templates:

• be careful with them if code-size is an issue. If your target CPU has no or only a very tiny ínstruction cache it may reduce the performance as well. (templates tend to bloat code if used without care). Otoh clever meta-programming can decrease the code-size as well. There is no clear cut answer on his.

Virtual functions and inheritance:

• These are fine for me. I write almost all of my embedded code in C. That does not stop me from using function-pointer tables to mimic virtual functions. They never became a peformance problem.