What's the use of suffix `f` on float value

Question

I am wondering what the difference is between these two variables in C:

float price = 3.00;

and

float price = 3.00f;
         


        

Answer 1

Because by unsuffixed floating-point literals are doubles, and rounding means that even small literals can take on different values when rounded to float and double. This can be observed in the following example:

float f=0.67;
if(f == 0.67) 
  printf("yes");
else 
  printf("no");  

This will output no, because 0.67 has a different value when rounded to float than it does when rounded to double. On the other hand:

float f=0.67;
if(f == 0.67f) 
  printf("yes");
else 
  printf("no"); 

outputs yes.

The suffix can be specified using either upper or lowercase letters.

Try this also:

printf(" %u %u\n", sizeof(.67f), sizeof(.67));

Check @codepade