C++ 四舍五入到最接近的数字倍数
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Round to nearest multiple of a number
提问by Luchian Grigore
Is there an idiomatic way to round to the nearestmultiple of a number, short of rounding both up and down and seeing which one is closest?
是否有一种惯用的方法可以舍入到最接近的数字倍数，而不是向上和向下舍入并查看哪个最接近？
Assume only integers:
假设只有整数：
number multiple result
12 5 10
13 5 15
149 10 150
回答by Mike Seymour
Add half of the multiple, then round down.
添加倍数的一半，然后向下取整。
result = ((number + multiple/2) / multiple) * multiple;
or
或者
result = number + multiple/2;
result -= result % multiple;
This rounds up if the number is exactly in the middle. You might need to tweak the calculation if you want different behaviour in that case. Also, beware overflow if numbermight be near the top of the type's range.
如果数字正好在中间，则四舍五入。如果您想要在这种情况下不同的行为，您可能需要调整计算。此外，如果number可能接近类型范围的顶部，请注意溢出。
回答by Muhamad Iqbal
I've answered this before on Rounding off a number to the next nearest multiple of 5
我之前在将数字四舍五入到下一个最接近的 5 的倍数上回答了这个问题
With using cmath::abs
随着使用 cmath::abs
int rounded = n + abs((n % denom) - denom);
You can change denomwith any denomination you want
您可以更改denom任何您想要的面额
