Rounding doubles - .5 - sprintf

c++, printf, rounding

Solution

It seems you have to use math round function for correct rounding.

printf("%.2f %.2f\n", 5.555, round(5.555 * 100.)/100.);

This gives the following output on my machine:

5.55 5.56

Problem

I'm using the following code for rounding to 2dp: ``` sprintf(temp,"%.2f",coef[i]); //coef[i] returns a double ``` It successfully rounds 6.666 to 6.67, but it doesn't work properly when rounding 5.555. It returns 5.55, whereas it should (at least in my opinion) return 5.56. How can I get it to round up when the next digit is 5? i.e. return 5.56. edit: I now realise that this is happening because when I enter 5.555 with cin it gets saved as 5.554999997. I'm going to try rounding in two stages- first to 3dp and then to 2dp. any other (more elegant) ideas?

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