#include <iostream>
 using namespace std;
 void f();
 int main(){
      f();
 }
 void f(){
     cout << "Hello Stackoverflow!" << endl;
 }
If I wanted to succeed in making this function inline, would I need to specify inline in the declaration or definition, or both? I know that inline functions are normally defined in headers so normally there shouldn't be a separate declaration, but I was curious about the few unique cases where there are.