about rounding off numbers

Hi,

I have a small question.

If i need to round off a number to int, i do it like
int j = (int)(4.8);
thus "j" will have value 4;

but my requirement is to see that if the value is 4.8 then "j" should take value as 5 and if the value is 4.3 then "j" should take value as 4.

How can I do this in C++.

Thanks!!

re: about rounding off numbers

Use a stringstream:
The notion of doing a cast is not rounding. That is covering up a compiler warning about truncation an possible loss of data.

The Rounder() function just reads the double into a stringstream and then extracts it as an int, char , int. Now you can make a test on the decmal portion and decide whether to increment the result or not.

Remember, when you cast in C++ you a) are calling a relic C function with a void* argument or b) your C++ design is faulty.

re: about rounding off numbers

Thanks for the clear explanation!!

re: about rounding off numbers

Hi,

the above is applicable only when i have a value between 4 and 5.
But in my program I am computing certain values and those values change each time in the loop. then in such case how can i round off as above??

do we have any in built functions for that??

Thanks!!

re: about rounding off numbers

No it is not limited to that range only.

re: about rounding off numbers

Another option is to add 0.5 onto the number and then floor it, and then cast the result to an int.

if num is a double variable, then this would do it:

I believe you'll need to include <cmath> to use the floor function.

this works because the floor function always rounds down, and any number that with a decimal of .5 or higher is raised to the next integer before being rounded. so that with 4.3 is increased to 4.8 and then floored giving you 4; while 4.8 would be raised to 5.3 which is floored to 5.

This is assuming that you want a decimal value of .5 to round up, if you want .5 to round down, then you can do this:

again needing to include <cmath> would be required.