c#中的除零异常

Question

static void Main(string[] args)
        {
                Console.WriteLine("请输入两个数和一个运算符：");
                float m = Convert.ToInt32(Console.ReadLine());
                float n = Convert.ToInt32(Console.ReadLine());
                string l = Console.ReadLine();
                float sum = 0;
          try{                  
                switch (l)
                {
                    case "+":
                        sum = m + n; break;
                    case "-":
                        sum = m - n; break;
                    case "*":
                        sum = m * n; break;
                    case "/":
                       
                            sum = m / n;
                        break;
                }
              }
            catch (System.DivideByZeroException e)
            { Console.WriteLine("出现异常" + e.Message); }
                Console.WriteLine("结果为{0}", sum);
       }
为什么不能捕获除零异常？怎么样才能捕获除零异常？

Answer 1

除以0 无限大  
int i = 5f;  
int j = 0/ （i-5);  
Console.WriteLine(j);  catch(DivideByZeroException e)  
{  
System.Console.WriteLine("零不能作为除数！异常值为：\n{0}",e);  
}  
catch(Exception e)  
{  
System.Console.WriteLine("并非\''零作为除数引发的异常\"!异常值为：\n{0}",e);  
}  

Answer 2

  case "/":
    if(n!=0)
{
  sum = m / n;
}
else
{
  //throw  Exception
}