我想用switch语句实现下面这样的情况.

Question

不能直接用.因为CASE语句必须是一个具体的值,除非你先判断X的值进行转换,不过那样也没什么意义呀.建议不如直接用IF

Answer 1

            int x = -1;
            switch (Math.Sign(x))
            {
                case 1:
                    MessageBox.Show("1");
                    break;
                case 0:
                    MessageBox.Show("0");
                    break;
                case -1:
                    MessageBox.Show("-1");
                    break;
            }

Answer 2

不行，case后面不能接表达式的。必须是具体的值。用if else 吧 

Answer 3

用Math.Sign(x)判断实现，二楼方法就行

Answer 4

switch (x >= 0)
        {
            case true:
                switch (x == 0)
                {
                    case true:
                        text.Text = "等于0";
                        break;
                    case false:
                        text.Text = "大于0";
                        break;
                }
                break;            case false:
                text.Text = "小于0";
                break;
        }

Answer 5

            int x = -1;
            switch (Math.Sign(x))
            {
                case 1:
                    y=1;
                    break;
                case 0:
                    y=0;
                    break;
                case -1:
                    y=-1;
                    break;
            }

Answer 6

多谢各位高人,特别多谢2楼的朋友.
9楼的朋友的好像和if语句无区别,只是if语句的变形,不过也多谢你.

Answer 7

我再提一个问题,将上面改为这样呢?y=1  当x>2 
  0  当x==2 
  -1 当x <2请问如何实现.只能用switch语句,不能用if语句.