In the previous blog, I shared the enumerations and structures in C#, this time I will share the arrays. Here we mainly focus on the maximization of the array and the sorting of the array.
One, mind map
What is an array?
A set of numbers of the same data type
What are the benefits of arrays?
Declare the same type of numbers at once
How to declare the four ways of array?
//第一种方式
int[] num1 = new int[10]; //长度为10，下标为0-9，int类型
//第二种方式
int[] num2 = new int[] { 1,2,3,4,5}; //此数组就存5个值
//第三种方式
int[] num3 = new int[3] { 1, 2, 3 }; //个数和声明数必须一致。此数组就存3个值，值都清楚
//第四种方式
int[] num4 = { 1, 2, 3, 4, 5 }; //简写法
How to assign a value to an array?
int[] num1 = new int[10]; //长度为10，下标为0-9，int类型
num1[8] = 20; //给8这个地方赋个值
Console.WriteLine(num1[8]);
Console.ReadKey();For example, if you build a building with 10 floors, if there is an open house, it will look for this room with the 6th floor number 100.
2. Actual combat drills
1. After a Chinese test, the teacher asks the class leader to count the scores of each student and calculate the average score of the whole class (a total of 5 students in the class), and then display all the results.
Console.WriteLine("请输入班级人数"); //用户输入人数
int number = 0; //平均成绩
int sum = 0; //总成绩
if (int.TryParse(Console.ReadLine(), out number)) //如果用户输入的人数正确
{
int[] score = new int[number]; //声明一个数组用来存放成绩
for (int i = 0; i < score.Length; i+1)
{
Console.WriteLine("请输入第{0}个人的成绩", i++); //用户输入成绩
score[i] = int.Parse(Console.ReadLine()); //把用户输入的成绩转换为int类型并存到数组中
sum += score[i]; //对分数进行求和
}
Console.WriteLine("总成绩为{0},平均成绩为{1}",sum,sum/number);
}
else //如果用户输入的人数错误
{
Console.WriteLine("输入有误");
}
Console.ReadKey();
2. Find the maximum, minimum, average, and sum of an array
int[] nums = { 1, 2, 3, 0, 9 };
int max = int.MinValue; //求最大值
int min = int.MaxValue; //求最小值
int sum = 0; //总和初始化为0
for (int i = 0; i < nums.Length ; i++)
{
if(nums[i]> max) //求最大值
{
max = nums[i];
}
if(nums[i]< min) //求最小值
{
min = nums[i];
}
sum += nums[i]; //求和
}
Console.WriteLine("最大值为{0}，最小值为{1}，总和为{2}，平均值为{3}",max,min,sum,sum/nums.Length );
Console.ReadKey();
3. Bubble sort
int[] nums = new int[] { 98, 54, 54, 322, 43, 23 }; //一个数组nums，并赋值（要被排序的数组）
int temp = 0;
for (int i = 0; i < nums.Length - 1; i++) //循环的轮数，需要6-1=5轮
{
for (int j = 0; j < nums.Length - 1 - i; j++) //比较的次数（随着轮数的增加，比较次数减少）
{
if (nums[j] > nums[j + 1]) //相邻两数进行比较，如果前一位>后一位
{
temp = nums[j]; //交换位置
nums[j] = nums[j + 1];
nums[j + 1] = temp;
}
}
}
for (int i = 0; i < nums.Length ; i++) //循环输出排序之后的数组元素
{
Console.Write(nums[i]+"\t"); //在控制台输出结果，并排序（\t)
}
Console.ReadKey();
4. Array sort
Method one, forward output
int[] nums = new int[] { 1, 2, 4, 3, -1 }; //定义一个数组，并赋值
Array.Sort(nums); //Array类，对数组元素进行排序
for (int i = 0; i < nums.Length ; i++) //for循环输出数组元素
{
Console.Write(nums[i] + "\t"); //在控制台输出内容，注：\t是水平制表符
}
Console.ReadKey();Method two, reverse output
int[] nums = new int[] { 1, 2, 4, 3, -1 }; //定义一个数组，并赋值
Array.Sort(nums); //Array类，对数组元素进行排序
//Array.Reverse(nums); //反转，颠倒原来数组，如，颠倒后：-1，3，4，2，1
for (int i = nums.Length - 1; i >= 0; i--) //倒着输出结果
{
Console.Write(nums[i] + "\t");
}
Console.ReadKey();
5. Use array method calls: calculate the maximum, minimum, average, and sum of all elements of an array
class Program
{
static void Main(string[] args)
{
Program.ArraySort(); //调用ArraySort这个方法
Console.ReadKey();
}
public static void ArraySort() //写了一个ArraySort方法，对数组进行排序
{
int[] nums = new int[] { 2, 3, 43, 23, 243, 3 }; //定义一个数组，并赋初值
int max = int.MinValue; //最大值
int min = int.MaxValue; //最小值
int sum = 0; //给求和赋初值为0
for (int i = 0; i < nums.Length; i++) //for循环，对数组进行遍历
{
if (nums[i] > max) //求最大值
{
max = nums[i];
}
if (nums[i] < min) //求最小值
{
min = nums[i];
}
sum += nums[i]; //求和
}
Console.WriteLine("最大值为：{0},最小值为：{1}", max, min); //在控制台输出最大值、最小值
Console.WriteLine("和为:{0},平均值为：{1}", sum, sum / nums.Length); //在控制台输出和、平均数
}
}
6. The names of people in the array (Bella, Edward, Jacob, Alice, Carlisle) are divided into: For example: "Bella|Edward..."
string[] names = new string[] { "贝拉", "爱德华", "雅各布", "爱丽丝", "卡莱尔", }; //定义一个字符串变量并赋值
string result = ""; //定义一个字符串result用来接收加|之后的元素
for(int i = 0; i < names.Length-1; i++) //for循环遍历数组元素
{
result += names[i] + "|"; //result=names某个元素+|
}
Console.WriteLine(result+names[names.Length -1]); //在控制台输出结果，最后一个元素不加“|”
Console.ReadKey();
7. Each element of an integer array is processed as follows: if the element is positive, the value of the element at this position is +1; if the element is negative, the value of the element at this position is -1; if the element is 0, The same
for (int i = 0; i < nums.Length; i++)
{
if(nums[i]>0) //如果数>0
{
nums[i]++;
}
if (nums[i] < 0) //如果数<0
{
nums[i]--;
}
}
for (int i = 0; i < nums.Length; i++) //循环输出数值
{
Console.Write(nums[i]+"\t");
}
Console.ReadKey();
8.forr: reverse, reverse the original array
Reverse the order of the elements of a string array: {"I", "Yes", "Good people"}{"Good people", "Yes", "I"}. Exchange the i-th and length-i-1th
方法一：Array.Reverse
string[] text = new string[] {"我", "是", "好人"}; //定义一个数组text并赋值
Array.Reverse(text); //反转
for (int i = 0; i < str.Length; i++) //遍历数组
{
Console.Write(str[i]+"\t"); //在控制台输出结果，注：\t是水平制表符
}
Console.ReadKey();
方法二：forr反转
Array.Sort(text);
for (int i = text.Length - 1; i >= 0; i--)
{
Console.Write(text[i] + "\t");
}
Console.ReadKey();
9. Array value and assignment
int[] nums = new int[5]; //声明一个数组
for (int i = 0; i < 5; i++) //赋值
{
nums[i] = 10;
}
for(int i = 0; i < 5; i++) //取值
{
Console.WriteLine(nums[i]);
}
Console.ReadKey();
Three, expand
Enumeration: a set of values in a fixed range
Structure: Declare multiple numbers of different data types at once
Array: Declare multiple numbers of the same data type at once