C# 如何将 Math.Ceiling 结果转换为 int？
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how to convert Math.Ceiling result to int?
提问by javapowered
Math.Ceilingreturns doublebecause doublemay store much bigger numbers.
However if i'm sure that inttype is capable to store the result how should I convert? Is it safe to cast (int) Math.Ceiling(...?
Math.Ceiling返回，double因为double可能存储更大的数字。但是，如果我确定该int类型能够存储结果，我应该如何转换？投射是否安全(int) Math.Ceiling(...？
采纳答案by ?yvind Br?then
If you are sure that you do not cross the capacity of int, it should be perfectly safe to do
如果您确定没有超过 int 的容量，那么这样做应该是完全安全的
int myInt = (int)Math.Ceiling(...);
If you are not sure about the bound, you could go with longinstead of int.
如果您不确定界限，则可以使用long代替int.
回答by Fredrik Johansson
I'd go with
我愿意
int x = (int)Math.Ceiling(0.9); // 1
回答by John Woo
int oInt = Convert.ToInt32(Math.Ceiling(value));
int oInt = Convert.ToInt32(Math.Ceiling(value));
since Math.Ceilingreturns doubleand you want to convert it to int, use ConvertClass.
example:
由于Math.Ceiling返回double并且您想将其转换为int，请使用ConvertClass。
例子：
double[] values= { Double.MinValue, -1.38e10, -1023.299, -12.98,
0, 9.113e-16, 103.919, 17834.191, Double.MaxValue };
int result;
foreach (double value in values)
{
try {
result = Convert.ToInt32(value);
Console.WriteLine("Converted the {0} value '{1}' to the {2} value {3}.",
value.GetType().Name, value,
result.GetType().Name, result);
}
catch (OverflowException) {
Console.WriteLine("{0} is outside the range of the Int32 type.", value);
}
}
// -1.79769313486232E+308 is outside the range of the Int32 type.
// -13800000000 is outside the range of the Int16 type.
// Converted the Double value '-1023.299' to the Int32 value -1023.
// Converted the Double value '-12.98' to the Int32 value -13.
// Converted the Double value '0' to the Int32 value 0.
// Converted the Double value '9.113E-16' to the Int32 value 0.
// Converted the Double value '103.919' to the Int32 value 104.
// Converted the Double value '17834.191' to the Int32 value 17834.
// 1.79769313486232E+308 is outside the range of the Int32 type.
回答by Mharlin
If you are uncertain you can always put an if statement and check if the number you get back is highter then int.MaxValue
如果您不确定，您可以随时添加 if 语句并检查您返回的数字是否更高 int.MaxValue
回答by Aurimas Neverauskas
From C++ practices, I would use the following. It's guaranteed to get the correct result even when ceiling returns 99.99999...8 or 100.000000...1
从 C++ 实践中，我将使用以下内容。即使天花板返回 99.99999...8 或 100.000000...1 也能保证得到正确的结果
var result = (int)(Math.Ceiling(value) + 0.5);
The code below should work too if you trust its implementation
如果您相信它的实现，下面的代码也应该可以工作
var result = Convert.ToInt32(value);
回答by Todd
If it's all about speed, then Math.Ceiling for Int inputs and output is quite slow. The fastest is an inline expression:
如果一切都与速度有关，那么用于 Int 输入和输出的 Math.Ceiling 会非常慢。最快的是内联表达式：
var ceilingResult = (value / divisor) + (value % divisor == 0 ? 0 : 1);
From my own benchmark of 10M iterations, Math.Ceiling takes ~2.4 seconds. Calling this expression inside a named function takes ~380 ms and having it as a direct inline expression takes ~33ms.
从我自己的 1000 万次迭代基准来看，Math.Ceiling 需要大约 2.4 秒。在命名函数内调用此表达式需要约 380 毫秒，而将其作为直接内联表达式需要约 33 毫秒。
If you would like Math.Floor for Int inputs and Output, it's even easier:
如果您希望使用 Math.Floor 进行 Int 输入和输出，则更简单：
var floorResult = (value / divisor);
