我如何用c#优雅地做到这一点?
例如,一个数字可以是1到100之间。
我知道一个简单的if (x >= 1 && x <= 100)就足够了;但是有很多语法糖和新特性不断添加到c# /。Net这个问题是关于更习惯的(一个可以称之为优雅的)写法。
性能不是问题,但请在非O(1)的解决方案中添加性能说明,因为人们可能会复制粘贴建议。
我如何用c#优雅地做到这一点?
例如,一个数字可以是1到100之间。
我知道一个简单的if (x >= 1 && x <= 100)就足够了;但是有很多语法糖和新特性不断添加到c# /。Net这个问题是关于更习惯的(一个可以称之为优雅的)写法。
性能不是问题,但请在非O(1)的解决方案中添加性能说明,因为人们可能会复制粘贴建议。
当前回答
if (value > 1 && value < 100)
{
// do work
}
else
{
// handle outside of range logic
}
其他回答
In production code I would simply write 1 <= x && x <= 100 This is easy to understand and very readable. Starting with C#9.0 we can write x is >= 1 and <= 100 Note that we must write x only once. is introduces a pattern matching expression where and is part of the pattern. && would require us to repeat x is as in x is >= 1 && x is <= 100 Here is a clever method that reduces the number of comparisons from two to one by using some math. There is not necessarily a performance advantage in doing so, but it is elegant. The idea is that one of the two factors becomes negative if the number lies outside of the range and zero if the number is equal to one of the bounds: If the bounds are inclusive: (x - 1) * (100 - x) >= 0 or (x - min) * (max - x) >= 0 If the bounds are exclusive: (x - 1) * (100 - x) > 0 or (x - min) * (max - x) > 0
如果这是偶然的,你只需要一个简单的If。如果这种情况在很多地方都发生,你可能会考虑这两个:
PostSharp。在方法编译后,用“注入”代码的属性来装饰方法。我不确定,但我可以想象它可以用来做这个。
喜欢的东西:
[Between("parameter", 0, 100)]
public void Foo(int parameter)
{
}
代码合同。优点是可以在编译时通过对代码和使用代码的地方进行静态验证来检查约束。
新花样的老最爱:
public bool IsWithinRange(int number, int topOfRange, int bottomOfRange, bool includeBoundaries) {
if (includeBoundaries)
return number <= topOfRange && number >= bottomOfRange;
return number < topOfRange && number > bottomOfRange;
}
if (value > 1 && value < 100)
{
// do work
}
else
{
// handle outside of range logic
}
像这样的怎么样?
if (theNumber.isBetween(low, high, IntEx.Bounds.INCLUSIVE_INCLUSIVE))
{
}
扩展方法如下(已测试):
public static class IntEx
{
public enum Bounds
{
INCLUSIVE_INCLUSIVE,
INCLUSIVE_EXCLUSIVE,
EXCLUSIVE_INCLUSIVE,
EXCLUSIVE_EXCLUSIVE
}
public static bool isBetween(this int theNumber, int low, int high, Bounds boundDef)
{
bool result;
switch (boundDef)
{
case Bounds.INCLUSIVE_INCLUSIVE:
result = ((low <= theNumber) && (theNumber <= high));
break;
case Bounds.INCLUSIVE_EXCLUSIVE:
result = ((low <= theNumber) && (theNumber < high));
break;
case Bounds.EXCLUSIVE_INCLUSIVE:
result = ((low < theNumber) && (theNumber <= high));
break;
case Bounds.EXCLUSIVE_EXCLUSIVE:
result = ((low < theNumber) && (theNumber < high));
break;
default:
throw new System.ArgumentException("Invalid boundary definition argument");
}
return result;
}
}