C# as 和 is 运算符区别和用法示例解析

            string title = "Hello DotNetGuide";
            if (title is string)
            {
                Console.WriteLine("是 string 类型");
            }
            else
            {
                Console.WriteLine("不是 string 类型");
            }
            if (title is not null)
            {
                Console.WriteLine("不为 null");
            }
            else
            {
                Console.WriteLine("为 null");
            }

            object obj = "追逐时光者";
            if (obj is string str)
            {
                Console.WriteLine($" {str}");
            }
            else
            {
                Console.WriteLine("不是指定类型");
            }

int[] empty = [];
int[] one = [1];
int[] odd = [1, 3, 5];
int[] even = [2, 4, 6];
int[] fib = [1, 1, 2, 3, 5];
Console.WriteLine(odd is [1, _, 2, ..]);   // false
Console.WriteLine(fib is [1, _, 2, ..]);   // true
Console.WriteLine(fib is [_, 1, 2, 3, ..]);     // true
Console.WriteLine(fib is [.., 1, 2, 3, _ ]);     // true
Console.WriteLine(even is [2, _, 6]);     // true
Console.WriteLine(even is [2, .., 6]);    // true
Console.WriteLine(odd is [.., 3, 5]); // true
Console.WriteLine(even is [.., 3, 5]); // false
Console.WriteLine(fib is [.., 3, 5]); // true

            object title = "Hello DotNetGuide";
            string str = title as string;
            if (str != null)
            {
                Console.WriteLine("是 string 类型: " + str);
            }
            else
            {
                Console.WriteLine("不是 string 类型");
            }
            int? num = title as int?;
            if (num.HasValue)
            {
                Console.WriteLine("是 int 类型: " + num.Value);
            }
            else
            {
                Console.WriteLine("不是 int 类型");
            }