Explanation of the example of the C# console with parameter program source code writing

using System;
using ;
using ;
using ;
namespace _1
{
class Program
{
static void Main(string[] args)
{
if ( < 1)
{
("Please enter parameter -a -v \"a s\"");
}
else
{
foreach (string key in args)
{
if (key == “a s”)
{
(“This is ‘a s' parameters”);
}
else if (key == “-a”)
{
(“This is ‘a' parameters”);
}
else if (key == “-v”)
{
(“This is ‘v' parameters”);
}
else
{
("Parameter error");
}
}
}
}
}
}