while循环

1、while结构

            int count = 0;//循环变量初始化

            while (count<5)//循环条件

            //循环体

            {

                Console.WriteLine(count);

                count++;循环变量增量；

            }

2、打印100到10000各位数和为7

            int num1 = 100;

            while (num1<10000) {

                if (num1/1000+num1%1000/100+num1%100/10+num1%10==7) {

                    Console.WriteLine(num1);

                }

                num1++;

            }

3、变量的作用域（作用范围）

循环练习

1、打印1到100偶数

            int i = 0;

            while (i<=100)

            {

                if (i%2==0) {

                    Console.WriteLine(i);

                }

                i++;

            }

2、打印1到100的和

            int sum = 0,c=1;

            while (c<=100) {

                sum = sum + c;

                c++;

            }

            Console.WriteLine(sum);

3、打印100到10000各位上不包含7的数；

            for (int i = 100; i < 10000; i++)

            {

                if (i / 1000 + i % 1000 / 100 + i % 100 / 10 + i % 10==7) {

                    Console.WriteLine(i);

                }

            }

4、打印100以内的偶数

            for (int i = 1; i < 100; i++)

            {

                if (i % 2 == 0) { Console.WriteLine(i); }

            }

5、打印1+2+3+。。。+100的和

            int sum = 0;

            for (int i = 1; i <= 100; i++)

            {

                sum += i;

            }

            Console.WriteLine(sum);

break和continue

1、break在switch语句里跳出开头，在循环结构里面跳出循环体；

            int i = 0;

            while (i < 5){

                if (i == 3) {

                    break;

                }

                Console.WriteLine("i");

                i++;

            }

            /*

            while (true)

            {

                int count=int.Parse( Console.ReadLine());

                if (count<0) { break;}

            }

            */

do,while

            /*

            int i = -10;

            while (i > 0) { Console.WriteLine(""); }

            */

            #endregion

for循环

1、for循环运在已知循环次数的情况

            for (int i =1;i<100;i++) { }

            int sum = 0;

            int n = 0;

            while (sum <= 10000) {

                n++;

                Console.WriteLine(n);

                sum = sum + n;

                Console.WriteLine(sum);

            }

循环嵌套

1、外层循环控制行数，内层循环控制列数

            for (int i = 1; i < 3; i++)

            {

                for (int j = 0; j < i; j++)

                {

                      Console.Write(i+" ");

                }

            }

2、打印99乘法表

            for (int i = 1; i <=9; i++)

            {

                for (int j = 1; j <=i; j++)

                {

                    Console.WriteLine();

                    Console.Write("{0}×{1}={2,-2}  ",j,i,i*j);

                }

                Console.WriteLine();

            }

一维数组

1、数组定义的语法格式

2、数组的初始化:5称为数组的长度，即数组中包含数据的个数，大括号里面每一个数据称为一个元素

3、new 是用来给数组在内存中开辟空间，此种初始化方法称为动态初始化

            int[] ages=new int[5] {2,3,4,5,6};

            ages = new int[] { 1, 2, 3, 4, 5, 6 };

4、此种情况系统给数组赋一个默认值：如果数组是数值类型（整形，浮点型），元素默认值为0

5、如果是字符串默认值为空，如果为bool类型，默认值为false

            ages = new int[5];

6、静态初始化

            int[] num = { 1, 2, 3, 4, 5 };

            ages[0] = 10;

7、数组作为一个整体不能直接参与运算，赋值可以

8、数组下标的最大值为数组长度减1

            /*nt sum = 0;*/

            for (int i = 0; i < ages.Length; i++)

            {

                sum = sum + ages[i];

                Console.WriteLine(ages[i]);

            }

            int[] intArr = { 3, 4, 6, 3, 213, 56, 32 };

9、反向打印数组

            for (int i = intArr.Length-1; i >-1 ; i--)

            {

                Console.WriteLine(intArr[i]);

            }

10、求和，求最大值和最小值

            int sum = 0,max=0,min=1000;

            for (int i = 0; i < intArr.Length; i++)

            {

                sum += i;

                if (max < intArr[i])

                {

                    max = intArr[i];

                }

                else if (min > intArr[i]) { min = intArr[i]; }

            }

            Console.WriteLine("求和"+sum);

            Console.WriteLine("最大值{0}，最小值{1}",max,min);