public static void ValueParam(string str)
{
str = "251";
}
public static void RefParam(ref string str)
{
str = "250";
}
public static void Main()
{
string str = "249";
ValueParam(str);
Console.WriteLine(" Value Param:"+str);
RefParam(ref str);
Console.WriteLine(" Ref Param:"+str);
}

public void ChageValue(int[] arr)
{
for(int i =0;i<arr.Length;i++)
arr[i]=0;
}
public static void Main()
{
int [] aar = {3,4,5,7,2,6,1};
for(int i=0;i<aar.Length;i++)
Console.WriteLine(">>>"+aar[i].ToString());
ChageValue(aar); // 这?没有使? REF 参数.
for(int i=0;i<aar.Length;i++)
Console.WriteLine("<<<"+aar[i].ToString());
}