else if和else语句上的表达式无效

Question

有一个错误表示'else if'和'else'

上的表达式无效

using System;

namespace test
{
    class MainClass
    {
        public static void Main (string[] args)
        {
            Random numberGenerator = new Random ();

            int num01 = numberGenerator.Next (1,11);
            int num02 = numberGenerator.Next (1,11);
            int realAnswer = num01 * num02 ;

            Console.WriteLine ("What is " + num01 + " multiplied by " + num02 + "?");

            int userAnswer = Convert.ToInt32 (Console.ReadLine ());

            if (userAnswer == realAnswer) {
                Console.WriteLine ("Good");
            } else if (userAnswer - realAnswer >= 1 && userAnswer - realAnswer <= 3) {

                int greater = numberGenerator.Next (1, 3);

                switch (greater) {
                case 1:
                    Console.WriteLine ("little too high");
                break;

                default:
                    Console.WriteLine ("little too much");
                    break;

                } else if (realAnswer-userAnswer  >= 1 && realAnswer-userAnswer  <=3) {

                    int less = numberGenerator.Next (1, 3);

                    switch (less) {
                    case 1:
                        Console.WriteLine ("little too low");
                        break;

                    default:
                        Console.WriteLine ("go higher!");
                        break;

                    } else {

                        Console.WriteLine ("you just suck");

                    }

                    Console.ReadKey ();

                    }
                }
        }
    }
}

Answer 1

在两个开关之后你都缺少结束大括号（}）：

if (userAnswer == realAnswer) {
    Console.WriteLine ("Good");
} else if (userAnswer - realAnswer >= 1 && userAnswer - realAnswer <= 3) {

    int greater = numberGenerator.Next (1, 3);

    switch (greater) {
    case 1:
        Console.WriteLine ("little too high");
    break;

    default:
        Console.WriteLine ("little too much");
        break;

    } 
} // Was missing in the OP
else if (realAnswer-userAnswer  >= 1 && realAnswer-userAnswer  <=3) {

        int less = numberGenerator.Next (1, 3);

        switch (less) {
        case 1:
            Console.WriteLine ("little too low");
            break;

        default:
            Console.WriteLine ("go higher!");
            break;

        } 
} // Was also missing
else {
    Console.WriteLine ("you just suck");
}

Answer 2

在开关结束时忘记支撑：小心

public static void Main(string[] args)
        {
            Random numberGenerator = new Random ();

            int num01 = numberGenerator.Next (1,11);
            int num02 = numberGenerator.Next (1,11);
            int realAnswer = num01 * num02 ;

            Console.WriteLine ("What is " + num01 + " multiplied by " + num02 + "?");

            int userAnswer = Convert.ToInt32 (Console.ReadLine ());

            if (userAnswer == realAnswer) {
                Console.WriteLine ("Good");
            } else if (userAnswer - realAnswer >= 1 && userAnswer - realAnswer <= 3) {

                int greater = numberGenerator.Next (1, 3);

                switch (greater) {
                case 1:
                    Console.WriteLine ("little too high");
                break;

                default:
                    Console.WriteLine ("little too much");
                    break;
                }

                } else if ((realAnswer-userAnswer  >= 1) && (realAnswer-userAnswer  <=3)) {

                    int less = numberGenerator.Next (1, 3);

                    switch (less) {
                    case 1:
                        Console.WriteLine ("little too low");
                        break;

                    default:
                        Console.WriteLine ("go higher!");
                        break;
                    }
            } else {

                        Console.WriteLine ("you just suck");

                    }

                    Console.ReadKey ();

                    }