它们在功能上与正数相等。区别在于他们处理负数的方式。

例如:

Math.Floor(2.5) = 2
Math.Truncate(2.5) = 2

Math.Floor(-2.5) = -3
Math.Truncate(-2.5) = -2

MSDN链接: ——数学。楼的方法 ——数学。截断方法

附注:小心数学。周围可能不是你期望的那样。

要获得“标准”舍入结果，请使用:

float myFloat = 4.5;
Console.WriteLine( Math.Round(myFloat) ); // writes 4
Console.WriteLine( Math.Round(myFloat, 0, MidpointRounding.AwayFromZero) ) //writes 5
Console.WriteLine( myFloat.ToString("F0") ); // writes 5

数学。地板滑到左边… 数学。细胞向右滑动… 数学。截断criiiiss croooss(地板/天花板始终朝向0) 数学。圆润恰恰，非常流畅……(走到最近的一边)

让我们开始工作吧!(⌐□_□)

向左……Math.floor 你们现在都收回来……-- 这次跳了两下……- = 2

大家鼓掌✋✋

你能走多低?你能往下走吗?一直到地板上?

if (this == "wrong")
    return "i don't wanna be right";

Math.truncate(x)也与int(x)相同。 通过去掉一个正的或负的分数，你总是趋向0。

Math.Floor()舍入到负无穷

数学。向上或向下截断舍入到零。

例如:

Math.Floor(-3.4)     = -4
Math.Truncate(-3.4)  = -3

而

Math.Floor(3.4)     = 3
Math.Truncate(3.4)  = 3

以下是MSDN对以下内容的描述:

Math.Floor, which rounds down towards negative infinity. Math.Ceiling, which rounds up towards positive infinity. Math.Truncate, which rounds up or down towards zero. Math.Round, which rounds to the nearest integer or specified number of decimal places. You can specify the behavior if it's exactly equidistant between two possibilities, such as rounding so that the final digit is even ("Round(2.5,MidpointRounding.ToEven)" becoming 2) or so that it's further away from zero ("Round(2.5,MidpointRounding.AwayFromZero)" becoming 3).

下面的图表可能会有所帮助:

-3        -2        -1         0         1         2         3
 +--|------+---------+----|----+--|------+----|----+-------|-+
    a                     b       c           d            e

                       a=-2.7  b=-0.5  c=0.3  d=1.5  e=2.8
                       ======  ======  =====  =====  =====
Floor                    -3      -1      0      1      2
Ceiling                  -2       0      1      2      3
Truncate                 -2       0      0      1      2
Round (ToEven)           -3       0      0      2      3
Round (AwayFromZero)     -3      -1      0      2      3

请注意，Round比它看起来强大得多，因为它可以舍入到特定的小数点后数位。其他的都是0小数。例如:

n = 3.145;
a = System.Math.Round (n, 2, MidpointRounding.ToEven);       // 3.14
b = System.Math.Round (n, 2, MidpointRounding.AwayFromZero); // 3.15

对于其他函数，你必须使用乘除技巧来达到相同的效果:

c = System.Math.Truncate (n * 100) / 100;                    // 3.14
d = System.Math.Ceiling (n * 100) / 100;                     // 3.15

Math.Floor()轮 "朝向负无穷"符合IEEE标准754第4节。

Math.Truncate()舍入“最接近零的整数”。

一些例子:

Round(1.5) = 2
Round(2.5) = 2
Round(1.5, MidpointRounding.AwayFromZero) = 2
Round(2.5, MidpointRounding.AwayFromZero) = 3
Round(1.55, 1) = 1.6
Round(1.65, 1) = 1.6
Round(1.55, 1, MidpointRounding.AwayFromZero) = 1.6
Round(1.65, 1, MidpointRounding.AwayFromZero) = 1.7

Truncate(2.10) = 2
Truncate(2.00) = 2
Truncate(1.90) = 1
Truncate(1.80) = 1