A test inline example question, I hope you all help

weiba0110

Qian Neng's C ++ has an example of such an inline function:
#include <iostream>
#include <time.h>
#include <conio.h>
using namespace std;
int calc1 (int x, int y) {return x + y;}
inline int calc2 (int x, int y) {return x + y;}
main ()
{int x [1000], y [1000], z [1000];
 clock_t t = clock ();
 for (int i = 0; i <1000; i ++)
  for (int j = 0; j <1000; j ++)
   for (int k = 0; k <1000; k ++)
     z [i] = calc1 (x [j], y [k]);
 cout << "NOT USING INLINE:" << (clock ()-t) / CLK_TCK << "seconds\n";
   t = clock ();
    for (int i = 0; i <1000; i ++)
     for (int j = 0; j <1000; j ++)
      for (int k = 0; k <1000; k ++)
       z [i] = calc2 (x [j], y [k]);
 cout << "USING INLINE:" << (clock ()-t) / CLK_TCK << "seconds\n";
 getchar ();
 }

The result in the book is that the function without inlining is 8.281 seconds
The function with inlining is 2.437 seconds.
The two functions obtained by my machine are all 10 seconds, which fainted me.
Can anyone help me out ... Thanks in advance.

珈蓝易拉罐

Compilers that don't, different compilation options, the results will be different, what's wrong with this

verance

If optimization is added, it is possible that your function will be automatically inlined.

So you can try to use the compiled command without optimization, and don't add debugging information,
Re-run may have different results

-IMHO, it is sometimes not easy to exclude all compiler optimizations, but is inlining really true?
In many compilers you can control yourself, unless your inlining is really unreasonable

(An example is if your inlining is a recursive function, then when the recursion reaches a certain level,
Or that the number of recursion layers exceeds the limit, then the compiler still uses a non-inline method to avoid the uncontrolled expansion of binary code)

verance

Some of the off-topics, your problem may be a sentence: although you write a non-inline function, but
The compiler felt that your non-inline function was simple enough, so it was treated as inline

So all you have to do is tell the compiler, don't just inline, just as I said! !!
For example vc compiler, you can use this command line to compile
cl / EHsc / Ob1 a.cpp

weiba0110

I use dev C ++, no VC