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c#之函数

原作者: [db:作者] 来自: [db:来源] 收藏 邀请

1.函数

1.函数

/// <summary>
/// main
/// 主函数（主方法）控制台的输出输入控制函数
/// </summary>
/// <param name="args">字符串参数</param>
static void Main(string[] args) //static 静态修饰符，void（int,string char）是无返回值+方法名（参数）{ 方法体}
{
int num1 = int.Parse(Console.ReadLine());
int num2 = int.Parse(Console.ReadLine());

string num3= GetMax(num1, num2);
Console.WriteLine(num3);


//Run();
//ChangeSelf();
//Run();
//ChangeSelf();
//int num1 = 10;
//Console.WriteLine(num1);
//return ; //结束当前方法
//int num2 = 20;
//Console.WriteLine(num2);

}
public static string GetMax(int num1,int num2) 
{

int num3 = num1 > num2 ? num1 : num2;
//Console.WriteLine(num3);
return num3+"";
}
public static void Run() {

Console.WriteLine("超级玛丽，跑啊跑，跳啊跳");
Console.WriteLine("超级玛丽，跑啊跑，跳啊跳");
Console.WriteLine("超级玛丽，跑啊跑，跳啊跳");
Console.WriteLine("超级玛丽，跑啊跑，跳啊跳");
Console.WriteLine("超级玛丽，跑啊跑，跳啊跳"); 
}
public static void ChangeSelf() {

Console.WriteLine("遇见一个砖块，撞一下无敌");
Console.WriteLine("屏幕闪烁，身体变大");
Console.WriteLine("遇到小怪，无敌消失");

}

 

例子1：
 public static int a = 3;
        static void Main(string[] args)//void 无返回值
        {
           // int a = 3;
            Text();
            Console.WriteLine(a);//作用域不同产生的结果不同
        }
        public static void Text() {
            a = a + 5;
        }
例子2：
 Console.WriteLine("请输入年份");
            string s = Console.ReadLine();
            year= IsInt(s);
           bool b= IsRun(year);

           Console.WriteLine("{0}是闰年吗？{1}", year, b);

        }
        public static int IsInt(string s) {
            int year;
            while (true)
            {
                try
                {
                    year = int.Parse(s);
                    return year;
                }
                catch 
                {
                    Console.WriteLine("您输入的有误，请在输入一次");
                    s = Console.ReadLine();
                }
            }
        
         
        }
        public static void Text()
        {
            a = a + 5;
        }
        public static bool IsRun(int year)
        {

            bool b = year % 400 == 0 || year % 4 == 0 && year % 100 != 0;
            return b;

        }
例子3：
//利用方法求两个数的和与积
            int num1 = 20;
            int num2 = 30;
          int[] s=  GetSum(52,63);//实参

          Console.WriteLine("和为{0}，积为{1}",s[0],s[1]);
        }
        public static int[] GetSum(int a, int b)//形参,变量名字与main的变量名字没有任何关系
        {
            //Console.WriteLine("和为" + (num1 + num2));
            //Console.WriteLine("积为" + (num1 * num2));
            int sum = a + b;
            int[] nums = { sum, (a * b) };
            return nums;
}
例子4：
int[] nums = {10,54,63,55,45,65,23,54,33,65,46 };
            int[] n=  GetResult(nums);
            foreach (var item in n)
            {
                Console.WriteLine(item);
            }
        }
        public static int[] GetResult(int[] nums)
        {
            int sum = 0;
            int avg = 0;
            int min = nums[1];
            int max=nums[5];
            for (int i = 0; i < nums.Length; i++)
            {
                if (nums[i]>max)
                {
                    max = nums[i];
                }
                if (nums[i]<min)
                {
                    min = nums[i];
                }
                sum += nums[i];
            }
            avg = sum / nums.Length;

            int[] n = { max,min,sum,avg};
            return n;
        
        }

 

using System;

namespace _002_函数
{
    class Program
    {
        static void Main(string[] args)
        {
            int year;
            Console.WriteLine("请输入年份");
            string s = Console.ReadLine();
            year = IsInt(s);
            bool b = IsRun(year);
            Console.WriteLine("{0}是闰年吗？{1}",year,b);
        }
        public static int IsInt(string s)
        {
            int year;
            while (true)
            {
                try
                {
                    year = int.Parse(s);
                    return year;
                }
                catch 
                {
                    Console.WriteLine("输入有误，请重新输入");
                    s = Console.ReadLine();
                }
            }
        }
        public static bool IsRun(int year)
        {
            bool b = year % 400 == 0 || year % 4 == 0 && year % 100 != 0;
            return b;
        }
    }
}

 

using System;

namespace _006_作业3
{
    class Program
    {
        static void Main(string[] args)
        {
         
            Console.WriteLine("请输入用户名和密码：");
            string name = Console.ReadLine();
            string mima = Console.ReadLine();
            int password = IsInt(mima);
            Name(name,password);
        }
        #region   判断密码
        public static int IsInt(string mima)
        {
            
            
            while (true)
            {
                int password = 0;
                try
                {
                    password = int.Parse(mima);
                    return password;
                }
                catch
                {
                    Console.WriteLine("密码输入有误，请重新输入");
                   
                     mima = Console.ReadLine();
                }
                
            }
             
        }
        #endregion
        #region      判断用户名和密码
        public static void Name(string name,int password)
        {
            int i = 1;
            while (i < 5)
            {
                if (name == "admin" && password == 123456)
                {
                    Console.WriteLine("登录成功");
                    break;
                }
                else
                {
                    Console.WriteLine("密码或用户名错误，请重新输入");
                    name = Console.ReadLine();
                    string mima = Console.ReadLine();
                    password = IsInt(mima);
                }
                i++;
            }
        }
        #endregion
    }
}

 

using System;

namespace _007_作业4_菲波那切数列
{
    class Program
    {
        static void Main(string[] args)
        {
            int a = 0;
            int b = 1;
            int index = SS(a, b);
            Console.WriteLine("斐波那数列第十个数为"+index);
    }
        public static int SS(int a,int b)
        {
            int c = 0;
                for (int i = 1; i < 9; i++)
                {
                c = a + b;
                a = b;
                b = c;
            }
            return c;
            }
        }
}

 

using System;

namespace _008_作业5_比较三个数大小
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("请输入三个数");
            int a = int.Parse(Console.ReadLine());
            int b = int.Parse(Console.ReadLine());
            int c = int.Parse(Console.ReadLine());
            IsInt(a, b, c);
        }
        public static void IsInt(int a,int b,int c)
        {
            int max = a > b ? a : b;
            max = max > c ? max : c;
            int min = a < b ? a : b;
            min = min < c ? min : c;
            int zj = (a + b + c) - max - min;
            Console.WriteLine("最大值为"+max+"中间值为"+zj+"最小值为"+min);
        }
    }
}

 

using System;

namespace _009_作业6_计算器
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("请输入要进行的计算，和数字");
           string c = Console.ReadLine();
            PanDuanFuHao(c);
        }
        #region    判断运算符
        public static void PanDuanFuHao(string c)
        {
            int a  = int.Parse(Console.ReadLine());
             
            int b = int.Parse(Console.ReadLine());

            switch (c)
            {
                case "+":
                    JF( a,b);
                    break;
                case "-":
                    JianF(a, b);
                    break;
                case "*":
                    CF(a, b);
                    break;
                case "/":
                    ChuF(a, b);
                    break;
                default:
                    Console.WriteLine("请重新输入");
                    break;
            }
            
        }
        #endregion
        #region     加
        public static void JF(int a,int b)
        {
            Console.WriteLine("和为"+(a+b));

        }
        #endregion
        #region     减
        public static void JianF(int a, int b)
        {
            Console.WriteLine("差为" + (a - b));

        }
        #endregion
        #region    乘
        public static void CF(int a, int b)
        {
            Console.WriteLine("积为" + (a * b));

        }
        #endregion
        #region  除
        public static void ChuF(int a, int b)
        {
            Console.WriteLine("商为" + (a / b));

        }
        #endregion
    }
}

 

 

2.

函数的重载
构成重载的条件：
1.方法名必须一样，参数列表不同（参数类型不同，参数个数不同）
2.与返回值无关

 static void Main(string[] args)
        {
            Sum(10,20);
                
            //方法构成重载的条件:1.方法名必须一样，参数列表不同（参数类型不同，参数个数不同）2.与返回值无关
            Console.WriteLine();

        }
        public static void Sum(int num1, int num2)
        {

            Console.WriteLine(num1 + num2);
        }
        public static int Sum(int num3, int num4,int num5)
        {
            return num3 + num4 ;
        }
        public static string Sum(int a, bool b) {
            return "";
        }
        public static void Sum(int num6, string num7) 
        {

            Console.WriteLine(num6+int.Parse(num7));
        
        }

 

using System;

namespace _014_函数的重载
{
    
    class Program
    {
        public static int MaxValue(params int[] arry)
        {
            int maxvalue = arry[0];
            for (int i = 1; i < arry.Length; i++)
            {
                if (arry[i] > maxvalue)
                {
                    maxvalue = arry[i];
                }
            }
            return maxvalue;
        }
        public static double MaxValue(params double[] arry)
        {
            double maxvalue = arry[0];
            for (int i = 1; i < arry.Length; i++)
            {
                if (arry[i] > maxvalue)
                {
                    maxvalue = arry[i];
                }
            }
            return maxvalue;
        }
        static void Main(string[] args)
        {
            int res = MaxValue(123, 25, 63);
            double res1 = MaxValue(3.14, 2.28, 56.3);
            Console.WriteLine(res1);
        }
    }
}

 

        
例子：ref
 static void Main(string[] args)
        {
            //ref
            int num = 20;
            int num1 = 30;
            int sum=0;
            Sum(ref  sum, num, num1);//ref:把实参中的值带入形参参与运算，运算完毕赋值再带出来(ref的值必须赋予初值)
            Sum(ref num,ref num1);
            Console.WriteLine(num+"  "+num1);
        }
        public static void Sum(ref int sum, int num, int num1)
        {
            sum = num + num1;
         
        }
        public static void Sum(ref int a,ref int b) 
        {
            int sum = a + b;
            a = a > b ? a : b;
            b = sum - a;
        
        
        }

 

using System;

namespace _015_ref
{
    class Program
    {
        static void Main(string[] args)
        {
            int num1 = 10;
            int num2 = 50;
            MaxValue(ref  num1,ref num2);//把实参的值带入形参参与运算，运算wanbi 赋值在带出来（ref值必须赋予初值）
            Console.WriteLine(num1+"    "+num2);
            
        }
        public static void MaxValue( ref int num1, ref int num2)
        {
            int sum = num1+num2;
            num1 = num1 > num2 ? num1 : num2;
            num2 = sum - num1;

        }
    }
}

 

例子：out
 Console.WriteLine("请输入数字");
            string num = Console.ReadLine();
            int number;
          bool b=  TryPase(num,out number);
          if (b)
          {
              Console.WriteLine(number);
          }
          else
          {
              Console.WriteLine(num);
          }

        }
        public static bool TryPase(string num,out int number) 
        {
            number = 0;
            try
            {
                number = int.Parse(num);
                return true;
            }
            catch 
            {

                return false;
            }
        
        
        }

 

using System;

namespace _016_out
{
    class Program
    {
        static void Main(string[] args)
        {
            int a = 12;
            int b = 2;
            Sum(out a, out b);
            Console.WriteLine(a + " " + b);
        }
        public static void Sum(out int a, out int b)
        {
            a = 100;
            b = 12;
            a = a + b;
        }
    }
}

 

using System;

namespace _018_out求和_平均值_
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] num = { 12, 25, 33, 42, 36 };
            Max(num, out int sum, out double average, out int max, out int min);
            Console.WriteLine(sum+" "+average+" "+max+" "+min);
        }
        public static void Max(int[]num1,out int sum,out double average,out int max,out int min)
        {
            
            sum = 0;
            max = int.MinValue;
            min = int.MaxValue;
            average = 0;
            for (int i = 0; i < num1.Length; i++)
            {
                if (num1[i] > max)
                {
                    max = num1[i];
                }
                if (num1[i] < min)
                {
                    min = num1[i];
                }
                sum += num1[i];
            }
            average = sum / num1.Length;
        }
    }
}

 

3.函数的递归

using System;

namespace _010_函数的递归调用
{
    class Program
    {
       public static  int F(int n)
        {
            if (n == 0) return 2;
            if (n == 1) return 3;
            return F(n - 1) + F(n - 2);
           
        }
        static void Main(string[] args)
        {
            //f(n)=f(n-1)+f(n-2) f(0)=2 f(1)=3 ,用程序求得f(40)
            int res = F(40);
            Console.WriteLine(res);

        }
    }
}
public static int i = 0;
        static void Main(string[] args)
        {
            //递归：自己的方法调用自己的方法就是递归
            //int num=0;
            //SayStory();
            //用递归求100以内正数的和
            int num = 100;
            int sum = GetSum(100);// getSumDG(99)+100//getSumDG(98)+99+100
            sum = GetSum(99) + 100;
            sum = (GetSumDG(98) + 99) + 100;
            sum = (GetSumDG(97) + 98) + 99 + 100;
        }
        public static int GetSumDG(int i)
        {
            if (i == 1)
            {
                return 1;
            }

            return GetSumDG(i - 1) + i;
            // getSumDG(99)+100

            //getSumDG(98)+99+100
             
                       
                    
                    
 
                      





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