doubles/printf & rounding

[wombat]

Is there a way to prevent rounding when using printf for print a
double/float?

Example:
double x=3.51;
printf("%.0f\n", x);



The output of this is 4, when I want it to be 3.

I've been surfing the net but I've been coming up empty. Big thanks for
any help.

 

[Jim Langston]

Is there a way to prevent rounding when using printf for print a
double/float?

Example:
double x=3.51;
printf("%.0f\n", x);



The output of this is 4, when I want it to be 3.

I've been surfing the net but I've been coming up empty. Big thanks for
any help.

printf("%.0f\n", x - 0.5);

This rounds down, but doesn't work correctly for negative x, in which case
you would want to add 0.5 (-3.51 - 0.5 = -4.01 so would be output as -4
instead of -3 as wanted).

 

[James Kanze]

Is there a way to prevent rounding when using printf for print a
double/float?

Example:
double x=3.51;
printf("%.0f\n", x);

The output of this is 4, when I want it to be 3.

I've been surfing the net but I've been coming up empty. Big thanks for
any help.

Nothing to do with printf: the same rules apply with the cleaner
iostreams. You can use floor() or ciel() to control how you
want rounded; C99 (and the next version of C++) add some more
(round() and trunc(), for example), which may already be
available with your compiler(s).