How will the preprocessor EXPAND the code?

[Anonymous]

[code:jrs19fyv]
#include<stdio.h>

#define USEFLOAT 0

int main(void)
{
int N;

#if USEFLOAT
   float X;
#else
   ;double X;
#endif
   printf("%lf", &X);
   return 0;
}
[/code:jrs19fyv]
This is what I have so far but when i complie it I get a runtime error, can anyone please help me solve this answer.

[Mr. Cool]

my compiles an error:
[quote:2ea242x0]C:\Program Files\Microsoft Visual Studio\MyProjects\test16b\t16b.cpp( : error C2601: 'N' : local function definitions are illegal
C:\Program Files\Microsoft Visual Studio\MyProjects\test16b\t16b.cpp( : error C2063: 'N' : not a function
C:\Program Files\Microsoft Visual Studio\MyProjects\test16b\t16b.cpp(15) : warning C4508: 'main' : function should return a value; 'void' return type assumed[/quote]

I think this means you can't perform anything since N is not declared anywhere in the body after initialization. You need to add N somewhere in order to get this to complie and run,sir.

[Anonymous]

This is the correct version

#include <stdio.h>

#define USEFLOAT 0

int main(void)
{
int N;

#if USEFLOAT
   float X;
#else
   double X;
#endif
   printf("%lf", &X);
   return 0;
}


However your compiler will still warn about not using the variable N. What was wrong was the:

#else
   ;double X;

The semikolon should not be there...easy fix..=)