floating point - Adding float values in c -

why f 0.0 after adding 0.1?

#include <stdio.h>  int main()   {     float f=0.0f;     f = f + 0.1f;     printf("f %f \n",&f);     return 0;   } 

sorry messed original question

why these 2 values not ? because of precision. sorry have ask question here because i'm blocked can't ask more questions

#include <stdio.h>  int main() {     float f=0.0f;     int i;      for(i=0;i<10;i++)           {f = f + 0.1f; }      if(f == 1.0f)             printf("f 1.0 \n");     else             printf("f %f not 1.0\n",f);      return 0; } 

 printf("f %f \n",f); 

gives correct output. see here-https://ideone.com/158zbv

to print address printf(" %p \n",&f); .

where printf statement give undefined behaviour.

about second code - can re-write if condition -

if(f>0.99f && f<1.01f) 

so gives correct output- https://ideone.com/karx3a

edit

while adding in program value of f not 1.0f may have different value ,when see value more decimal places bit different 1.0f that's why code go else part .

see here value f has every iteration-https://ideone.com/wj7u1r