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The latest version of this topic can be found at noinline.

Microsoft Specific
__declspec(noinline) tells the compiler to never inline a particular member function (function in a class).

It may be worthwhile to not inline a function if it is small and not critical to the performance of your code. That is, if the function is small and not likely to be called often, such as a function that handles an error condition.

Keep in mind that if a function is marked noinline, the calling function will be smaller and thus, itself a candidate for compiler inlining.

class X {  
   __declspec(noinline) int mbrfunc() {  
      return 0;   
   }   // will not inline  

inline, __inline, __forceinline