How do I round numbers up or down depending on the value in object C.. for example.
Lets say the number is 143 - I would want to round down to 140
but if the number is 146 - I would want to round up to 150
Assuming 145 should round to 150 (that's the standard in science and technology), the formula is:
x_rounded = ((x + 5)/10)*10;
More generally, when rounding to the nearest n, it's
x_rounded = ((x + n/2)/n)*n;
It comes from the fact that integer division always rounds down.
For negative numbers, it's slightly more tricky.
EDIT: also assuming it's all integers. With floats/doubles, better use the C math library, as division works differently. Like this:
#include <math.h> x_rounded = floor((x+5)/10) * 10;