C# 在两个数字之间切换？

Question

我正在尝试创建智能 switch 语句，而不是使用 20 多个 if 语句。我试过这个

private int num;
switch(num)
{
    case 1-10:
        Return "number is 1 through 10"
        break;
    default:
        Return "number is not 1 through 10"
}

它说案件不能互相失败。

感谢您的帮助！

Answer 1

您尝试使用 switch/case 进行范围设置的语法是错误的。

case 1 - 10: 将被翻译成 case -9:

您可以通过两种方式尝试覆盖范围（多个值）：

单独列出案例

case 1: case 2: case 3: case 4: case 5:
case 6: case 7: case 8: case 9: case 10:
    return "Number is 1 through 10";
default:
    return "Number is not 1 though 10";

计算范围

int range = (number - 1) / 10;
switch (range)
{
    case 0: // 1 - 10
        return "Number is 1 through 10";
    default:
        return "Number is not 1 though 10";
}

然而

您确实应该考虑使用 if 语句

覆盖值范围

if (1 <= number && number <= 10)
    return "Number is 1 through 10";
else
    return "Number is not 1 through 10";

Answer 2

不，switch case 中没有 "range" 的语法。如果您不想列出个别案例，那么 if/else 会更简洁：

if(num >= 1 && num <= 10)
    Return "number is 1 through 10";
else    
    Return "number is not 1 through 10";

也可以用条件运算符缩短：

return (num >= 1 && num <= 10)
    ? "number is 1 through 10"
    : "number is not 1 through 10";

我会使用最容易被其他人阅读和理解的那个。

Answer 3

通过最近的更改 introduced in C# 7，现在可以 switch 一个范围。

示例：

int i = 63;

switch (i)
{
    case int n when (n >= 10):
    Console.WriteLine($"I am 10 or above: {n}");
    break;

    case int n when (n < 10 && n >= 5 ):
    Console.WriteLine($"I am between 10 and 5: {n}");
    break;

    case int n when (n < 5):
    Console.WriteLine($"I am less than 5: {n}");
    break;
}

注意：这对 OP 确实没有太大帮助，但希望它能帮助将来寻找它的人。

Answer 4

我知道我来晚了，但万一有人想知道这是怎么做到的，请看这个例子：

public string IsBetween1And10(int num)
{
    return num switch
    {       
        >= 1 and <= 10 => "number is 1 through 10",
        _ => "number is not 1 through 10"
    };
}

C# 在两个数字之间切换？

C# Switch Between Two Numbers?

c#

switch-statement

然而