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
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;
}
}
其他回答
通过一些扩展方法的滥用,我们可以得到以下“优雅”的解决方案:
using System;
namespace Elegant {
public class Range {
public int Lower { get; set; }
public int Upper { get; set; }
}
public static class Ext {
public static Range To(this int lower, int upper) {
return new Range { Lower = lower, Upper = upper };
}
public static bool In(this int n, Range r) {
return n >= r.Lower && n <= r.Upper;
}
}
class Program {
static void Main() {
int x = 55;
if (x.In(1.To(100)))
Console.WriteLine("it's in range! elegantly!");
}
}
}
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;
}
}
我不知道,但我用这个方法:
public static Boolean isInRange(this Decimal dec, Decimal min, Decimal max, bool includesMin = true, bool includesMax = true ) {
return (includesMin ? (dec >= min) : (dec > min)) && (includesMax ? (dec <= max) : (dec < max));
}
这是我使用它的方式:
[TestMethod]
public void IsIntoTheRange()
{
decimal dec = 54;
Boolean result = false;
result = dec.isInRange(50, 60); //result = True
Assert.IsTrue(result);
result = dec.isInRange(55, 60); //result = False
Assert.IsFalse(result);
result = dec.isInRange(54, 60); //result = True
Assert.IsTrue(result);
result = dec.isInRange(54, 60, false); //result = False
Assert.IsFalse(result);
result = dec.isInRange(32, 54, false, false);//result = False
Assert.IsFalse(result);
result = dec.isInRange(32, 54, false);//result = True
Assert.IsTrue(result);
}
优雅是因为它不需要确定两个边界值中哪个先大。它也不包含分支。
public static bool InRange(float val, float a, float b)
{
// Determine if val lies between a and b without first asking which is larger (a or b)
return ( a <= val & val < b ) | ( b <= val & val < a );
}
这些是一些可以提供帮助的扩展方法
public static bool IsInRange<T>(this T value, T min, T max)
where T : System.IComparable<T>
{
return value.IsGreaterThenOrEqualTo(min) && value.IsLessThenOrEqualTo(max);
}
public static bool IsLessThenOrEqualTo<T>(this T value, T other)
where T : System.IComparable<T>
{
var result = value.CompareTo(other);
return result == -1 || result == 0;
}
public static bool IsGreaterThenOrEqualTo<T>(this T value, T other)
where T : System.IComparable<T>
{
var result = value.CompareTo(other);
return result == 1 || result == 0;
}