Thread: Output size

One can only guess at the OS/Compiler you're using...

> i.e. I dont know if having big int arrays ( int [] ) increase output size.
Generally speaking, if you initialise global data (in program data initialisations, then it will take up space in the executable image loaded from storage.
Eg.

Code:

int a[1000];  // probably goes in bss section

int a[1000] = { 0 };  // probably goes in data section

But then you have to make sure you initialise it at runtime.

> My application is designed mainly for speed, so I have set all compiler options for optimize for speed.
But unless your application takes well below 1 second of run-time, the amount of time to load the program from disk is going to be pretty minimal.
Saving 50mS in an hour doesn't count as an improvement - it's noise.

Here are some suggestions:
- Use constants instead of #define's.
- Create constants for commonly used strings that are identical in several locations.
- Read large arrays from a file instead of hard-coding the data in the code.

Unless your program is written really badly, you might be able to save 1-2 KB. Is it worth your time?

Originally Posted by Kempelen

What is the reason for this??? I have lot of #defs....

Because macros just copy and paste data all over the place, so you have multiple copies of the same data everywhere. Constants are only stored in one place.

Originally Posted by Kempelen

I dont see it. Macros are not data but machine instructions... or are you refering to macros which has a data declaration in it¿¿

Also I think is the same to use:
#define myint 10
than declare :
const int myint 10;

I dont see how this sample could be different in size.

Try these and you'll probably see a size difference:

Code:

#include <stdio.h>

#define str "blah, blah, blah..."

int main()
{
   printf( str );
   printf( str );
   printf( str );
   return 0;
}

Then replace the #define line with:

Code:

const char* str = "blah, blah, blah...";

and recompile.
You might need to turn off optimizations in your compiler.

*shrug*
The OP still hasn't answered what platform they're using, or the lifetime of the program.