floor(positive double) vs trunc(positive double) different

[Hicham Mouline]

If we consider a positive double argument, that is not 0, not NaN not
infinity.

do floor() and trunc() return the same value then?

Regards,

 

[Barry Schwarz]

If we consider a positive double argument, that is not 0, not NaN not
infinity.

do floor() and trunc() return the same value then?

floor() rounds down. trunc() rounds to 0. For positive values, and
0, the results are the same.

 

[Keith Thompson]

<snip part that made me laugh>

I think they have to return the exact same value under said circumstances.

C99 7.12.9.2 The floor functions p2

"The floor functions compute the largest integer value not greater than x."

C99 7.12.9.8 The trunc functions p2

"The trunc functions round their argument to the integer value,
**in floating format** [emphasis added], nearest to but no larger
in magnitude than the argument."

Do both return a float like trunc(), or does floor() return an integer?

Both return double (not float).

Hint: The best way to answer simple questions like that
is to read the documentation. If you don't have something
like "man floor" and/or "man trunc" on your system, you can
always grab a copy of the latest draft of the C standard from
<http://www.open-std.org/JTC1/SC22/WG14/www/docs/n1256.pdf>.