Thread: How to take only two decimals of float without rounding?

Originally Posted by cnewbie1

And the correct mathematical way to do this is to round it.

Being a cnewbie I don't know if there exists a easy way to specify x decimals without rounding. My first impulse would be to treat the float variable as a string and just cut away everything after .xx (all decimals after the second) manually.

Rounding is certainly the behavior that most people would expect, but I wouldn't say it's the correct way. Truncation is perfectly valid and correct, even if it's less used than rounding. The IEEE 754 floating point standard, which is what most systems conform to, specifies 5 rounding methods, including the truncation that the OP was interested in. Whether the OP has a fully conforming implementation and how s/he will set the rounding method, I can't say.

Originally Posted by stahta01

Look up the floor() function in IIRC math.h; might not do what you want but it or round() with division/multiplication should.

Try trunc() with some multiplication/division. It is also in math.h and avoids the problems you will encounter with floor and negative arguments.

anduril: Yup, you're right of course. Bad choice of words on my part.