C#程序设计 第2周题解

A. 计算两个数的和、差、商、积。

从键盘分别输入两个不为0的整数（前2行输入），分别输出这两个整数的和 差 积 商。

using System;
// Written by Sheauhaw Jang
// 2020-09-22 10:50:57
namespace CSharp_Week1_A
{
    public class Calculate
    {
        public static int Get(int a, int b, int type)
        {
            switch(type)
            {
                case 0: return a + b;
                case 1: return a - b;
                case 2: return a * b;
                case 3: return a / b;
            }
            return 0;
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            int a = Convert.ToInt32(Console.ReadLine());
            int b = Convert.ToInt32(Console.ReadLine());
            for (int i = 0; i < 4; ++i)
            {
                if (i > 0)
                    Console.Write(' ');
                Console.Write(Calculate.Get(a, b, i));
            }
        }
    }
}

B. 时间转换

输入表示时间的整数，单位是秒。输出*天*小时*分*秒。

如果时间单位前的数值是0，则不输出该时间单位的数值。

using System;
// Written by Sheauhaw Jang
// 2020-09-22 11:17:04
namespace CSharp_Week1_B
{
    public class TimeManager
    {
        public static long day = 60 * 60 * 24;
        public static long hour = 60 * 60;
        public static long minute = 60;
        public static long second = 1;
        public static long[] units = { day, hour, minute, second };
        public static string[] unitsName = { "天", "小时", "分", "秒" };
        public static long GetUnitCount(long tVar, int type)
        {
            if (type != 0)
                tVar %= units[type - 1];
            return tVar / units[type];
        }
        public static bool WriteUnitCount(long tVar, int type)
        {
            long ans = GetUnitCount(tVar, type);
            if (ans == 0)
                return false;
            Console.Write(ans);
            Console.Write(unitsName[type]);
            return true;
        }
        public static bool WriteCount(long tVar)
        {
            bool ans = false;
            for (int i = 0; i < units.Length; ++i)
                if (WriteUnitCount(tVar, i))
                    ans = true;
            return ans;
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            long tVar = Convert.ToInt64(Console.ReadLine());
            TimeManager.WriteCount(tVar);
        }
    }
}

C. 整数加密

对于一个4位整数（从0000-9999）按如下方式加密：将每位数字加7后对10取余，用余数替换原来的数字；然后将1,3位数字互换；2,4位数字互换。

输入一个4位数，输出加密后的结果。

using System;
// Written by Sheauhaw Jang
// 2020-09-22 11:44:47
namespace CSharp_Week1_C
{
    public class Encode
    {
        static int AddModulo(int x, int p) { return x >= p ? x - p : x; }
        static void Swap<T>(ref T a, ref T b)
        {
            T tmp = b;
            b = a;
            a = tmp;
        }
        public static int[] DoEncoding(string x)
        {
            int[] code = new int[x.Length];
            for (int i = 0; i < x.Length; ++i)
            {
                code[i] = x[i] - '0';
                code[i] = AddModulo(code[i] + 7, 10);
            }
            Swap(ref code[0], ref code[2]);
            Swap(ref code[1], ref code[3]);
            return code;
        }
        public static void WriteCode(string x)
        {
            int[] code = DoEncoding(x);
            foreach (int digit in code)
                Console.Write(digit);
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            string x = Console.ReadLine();
            Encode.WriteCode(x);
        }
    }
}

D. 字符串输入输出

输入一个字符串，按照样例格式输出。

样例：

Alice

Hi Alice,

Welcome to C# 2020!

Best wishes!

using System;
// Written by Sheauhaw Jang
// 2020-09-22 11:58:50
namespace CSharp_Week1_D
{
    class Program
    {
        static void Main(string[] args)
        {
            string s = Console.ReadLine();
            Console.WriteLine("Hi {0},", s);
            Console.WriteLine("Welcome to C# 2020!");
            Console.WriteLine();
            Console.WriteLine("Best wishes!");
        }
    }
}

E. 字符大小写转换

输入一个字母，如果它是小写字母则输出它的大写字母，如果它是大写字母输出它的小写字母。

using System;
// Written by Sheauhaw Jang
// 2020-09-22 21:28:37
namespace CSharp_Week1_E
{
    class Program
    {
        static void Main(string[] args)
        {
            int s = Console.Read();
            if (s >= 'a' && s <= 'z')
                s = s - 'a' + 'A';
            else
                s = s - 'A' + 'a';
            Console.WriteLine(Convert.ToChar(s));
        }
    }
}