我不明白为什么我会收到以下错误

Question

我很确定我完全正确。我在想不知何故我的语法是错误的，但我没有运气尝试谷歌为什么它是错误的。这是我的代码：

namespace Exercise1
{
    class Program
    {
        static void Main(string[] args)
        {
            Values aValue = new Values();

            //set array
            int[] number = new int[12];

            //ask user for input
            Console.WriteLine("Please enter a value between 0 and 10: ");
            aValue.InValue = Console.ReadLine(); //Read input
            aValue.IntValue = int.Parse(aValue.InValue); //convert string to int

            while (aValue.IntValue != -99) //user has not stopped program

                if (aValue.IntValue > 10 || aValue.IntValue < 0) //valid value
                    Console.WriteLine("Thank you! Please enter '-99' when you are ready to finsih.");
            aValue.InValue = Console.ReadLine(); //read input
            aValue.IntValue = int.Parse(aValue.InValue); //convert string to int
            number[aValue.IntValue]++; //add input to corresponding array box

????        else 
                Console.WriteLine("You have entered an invalid value.");
            aValue.InvalidValueCount()++;

            namespace Exercise1
            {
                class Values
                {
                    private string inValue;
                    public string InValue { get; set; }

                    private int intValue;
                    public int IntValue { get; set; }

                    private int validValueCount;
                    public int ValidValueCount { get; set; }

                    private int invalidValueCount;
                    public int InvalidValueCount() { 
                        invalidValueCount = 0;
                        return invalidValueCount;
                    }
                }
           }

错误信息如下：

表达式术语“else”无效
;预期（在“其他”之后）
只有赋值、调用、递增、递减、等待和新对象表达式可以用作语句（在“number[aValue.IntValue]++;”之后）
递增或递减运算符的操作数必须是变量、属性或索引器（在“aValue.InvalidValueCount()++;”之后）

感谢您的帮助！

Answer 1

while/if/else 之后的多行代码块需要大括号括起来

        while (aValue.IntValue != -99) //user has not stopped program
        { 
            if (aValue.IntValue > 10 || aValue.IntValue < 0) //valid value
            {
                Console.WriteLine("Thank you! Please enter '-99' when you are ready to finsih.");
                aValue.InValue = Console.ReadLine(); //read input
                aValue.IntValue = int.Parse(aValue.InValue); //convert string to int
                number[aValue.IntValue]++; //add input to corresponding array box
            }
            else 
            {
                Console.WriteLine("You have entered an invalid value.");
                aValue.InvalidValueCount()++; // <-- this is your error
            }
        }