c - float to int unexpected behaviour

Question

can you please explain the o/p behavior of this program.

int main()
{
  float a = 12.5;
  printf("%d
", a);
  printf("%d
", *(int *)&a);
  return 0;
} 

can you please check code at http://codepad.org/AQRlAzkC
why is this output coming ..

Answer 1

You don't want to cast the float pointer to an integer pointer. Floats and integers are not stored the same way and if you do that then there is no conversion that will take place, and thus you will get garbage printed to the screen. If however you cast an int-value to a float-value then the compile will convert the float from it's internal type into an integer for you. So you should replace the (int *) with (int).

Also, %d is for decimal(integer) values. What you want is %f, which is for float values, for the first printf.

What you want is this:

#include <stdio.h>

int main()
{
  float a = 12.5;
  printf("%f
", a); //changed %d -> %f
  printf("%d
", (int)a); //changed *(int *)& -> (int) for proper conversion
  return 0;
} 

verified here: http://codepad.org/QD4kzAC9