Visual C++ - enable optimizations and browse the optimized code - c++

Question

How I can compile my project with optimizations turned on and see what optimizations changed in my code.
For example:
My original code:
printf("Test: %d",52);
for (int empty=0;i<100000;i++) {
//Nothing here
}
Now when I compile my code with optimzations ,I want to see: (I think it'll be like that)
printf("Test: 52");

Answer 1

The compiler doesn't optimize modify the source code (what you've shown in your question), but the binary, which consists of asm instructions.
How you turn optimization on and off depends on the compiler, so you'll have to refer to its documentation.
In MSVS, you can choose this option from the top toolbar - look for Debug (un-optimized) vs Release (optimized). You can see the binary code by stepping through the code with the debugger, right click -> show dissasembly.
Your code, for example, generates:
Without optimizations:
printf("Test: %d",52);
0097171E mov esi,esp
00971720 push 34h
00971722 push offset string "Test: %d" (9788C8h)
00971727 call dword ptr [__imp__printf (97C3E0h)]
0097172D add esp,8
00971730 cmp esi,esp
00971732 call #ILT+575(__RTC_CheckEsp) (971244h)
for (int i=0;i<100000;i++) {
00971737 mov dword ptr [i],0
0097173E jmp wmain+49h (971749h)
00971740 mov eax,dword ptr [i]
00971743 add eax,1
00971746 mov dword ptr [i],eax
00971749 cmp dword ptr [i],186A0h
00971750 jge wmain+54h (971754h)
//Nothing here
}
00971752 jmp wmain+40h (971740h)
With optimizations:
printf("Test: %d",52);
013A1000 push 34h
013A1002 push offset string "Test: %d" (13A20F4h)
013A1007 call dword ptr [__imp__printf (13A209Ch)]
013A100D add esp,8
for (int i=0;i<100000;i++) {
//Nothing here
}