A Few Remarks About Inline Specifier

A Few Remarks About Inline Specifier

All member functions implemented within a class declaration are by default inline:

 //file:  A.hclass A {	int a;	public:	int Get_a() { return a; } //declaration + definition; 						//implicitly inline	void Set_a(int aa) { a = aa; } //ditto	void calc(int *result); //declaration only	//...}

Keep in mind, however, that whenever this .h file is #included, the code of the Geta() member function, as well as any other member function defined in the declaration file, is re-compiled. As a result, not only do you end up with longer compilation time, but you also may encounter longer linking time and difficulty to step into the function code during a debugging session. Therefore, it is best to implement all member functions in their corresponding .cpp file and leave only function prototypes in the .h file like this:

 //file:  A.hclass A {	int a;	public:	inline int Get_a(); //implemented in a separate .cpp file 	inline void Set_a(int aa);  	void calc(int *result); 	//...}//file: A.cpp#include "A.h"int A::Get_a() {	return a;}//etc..

By the way, even when defining these member functions separately, the inline specifier is most likely redundant, since any decent optimizer is clever enough to figure out automatically when a member function should be inlined. In other words, inline is almost never required.


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