C#中使用||运算符时While循环无限循环的原因咨询

你的C#代码如下：

namespace GuestBook
{
    internal class GuestTracker
    {
        
        public static (string fullName, int guestCount) NameLog()
        {
            int guestCount;

            Console.Write("Welcome to the Cliffview Venue, " +
                "Hubbard's Wedding check in, what is your first and last name? ");
            string fullName = Console.ReadLine();

            Console.Write($"\nHello {fullName} how many people will be joining you today? ");
            string guestCountText = Console.ReadLine();

            while (int.TryParse(guestCountText, out guestCount) == false)
            {
                Console.Write("\nSorry that wasn't a vaild number of guests, please entar a count using only the 0-9 characters: ");
                guestCountText = Console.ReadLine();

            }

            Console.Write($"So we have a total of {guestCount} guests, is this correct? ");
            string correctCount = Console.ReadLine();

            string no;
            while((no = correctCount.ToLower()) != "yes" || no != "no") 
            {
                Console.Write("\nI'm sorry, was that a yes or no? ");
                correctCount = Console.ReadLine();

            }

            if(correctCount.ToLower() == "no")
            {
                Console.Clear();
                Console.Write("\nOkay let's start over then.");
                NameLog();

            }


            return (fullName, guestCount);
        }



    }
}

无限循环的原因 #

你在第二个while循环里用了||（逻辑或）运算符，这个逻辑的核心问题是：无论用户输入什么，循环条件永远为true。

举两个关键场景就能看明白：

• 当用户输入yes时，no != "yes"是false，但no != "no"是true，false || true的结果是true，循环继续
• 当用户输入no时，no != "yes"是true，但no != "no"是false，true || false的结果还是true，循环继续

不管输入是yes、no还是其他内容，这个条件都会成立，循环根本停不下来，自然就陷入无限循环了。

你想要的逻辑是「当输入既不是yes也不是no时，继续循环」，这时候应该用&&（逻辑与）运算符，把条件改成：

while((no = correctCount.ToLower()) != "yes" && no != "no")

这样只有当输入既不是yes也不是no的时候，循环才会继续；只要输入yes或no，条件就会变成false，循环终止。

内容的提问来源于stack exchange，提问作者Zathus89