1. Definition
An array is a fixed-size sequential collection that stores elements of the same type. . An array is a collection used to store data. It is generally considered that an array is a collection of variables of the same type.
An array is a set of values of the same data type.
The data is a reference type, so it is stored in the heap memory.
2. Format
Data type [] variable name = new data type [size]
Example: int[] a = new int[10]
a. Declare the array first, then initialize the array
int[] a;
int[] a = new int[10];
b. Assign the array
int[] a = {1,2,3,4,5,6} while declaring the array ;
c. Create and initialize array
int[] a = new int[5] {1,2,3,4,5};
int[] a = new int[] {1,2,3,4,5}; (The size can be omitted)
3. Example
(1). Find the first 20 items of the sequence 1, 1, 2, 3, 5, 8... and sum them up.
//定义一个长度20的数组
int[] a = new int[20];
//先定义a[0],a[2]的值，然后通过相邻数相加得下一个数的规律，依次得出数组所有结果
a[0] = 1;
a[1] = 1;
int sum = 0;
for (int i = 2; i < 20; i++)
{
a[i] = a[i - 1] + a[i - 2];//得到数组中每一个下标对应的值
}
for (int j = 0; j < 20; j++)
{
Console.Write(a[j] + " ");//每循环一次，就输出一次
sum += a[j];//同时把每一个数加起来
}
Console.WriteLine();//换行，看着比较美观，可不要
Console.WriteLine(sum);
(2). Define an integer array with a length of 10, and input 10 integers in a loop. Then enter an integer, search for the integer, find the output subscript, and give a prompt if it is not found
Console.WriteLine("输入十个整数：");
int[] a = new int[10];
for (int i = 0; i < 10; i++)
{
Console.Write("第" + (i + 1) + "个整数：");
int n = int.Parse(Console.ReadLine());
a[i] = n;
}
Console.WriteLine("请输入一个整数：");
int flag = 0;//判断输入的整数是否存在
int num = int.Parse(Console.ReadLine());
for (int j = 0; j < 10; j++)
{
if (num == a[j])
{
Console.WriteLine("找到其下标为：" + j);
flag = 1;//如果存在，flag则为0
}
}
if (flag == 0)
{
Console.WriteLine("没有找到");}
(3). Now there is an array as follows: int oldArr[]={1,3,4,5,0,0,6,6,0,5,4,7,6,7,0,5} Requirements Remove the items with a value of 0 in the above array, and store the values that are not 0 into a new array, and the generated new array is: int newArr [] ={1,3,4,5,6,6,5, 4,7,6,7,5}
//思路：先找到该数组的长度，然后再把不为0的值存入新的数组
//自己做的方法太复杂了，可以跳过看下一个老师教的
int[] oldArr = {
1, 3, 4, 5, 0, 0, 6, 6, 0, 5, 4, 7, 6, 7, 0, 5 };//长度16
int n = 0;//判断0的数量，用来(oldArr.Length-n)得到非0数组的长度
int length;
for (int i = 0; i < oldArr.Length; i++)
{
if (oldArr[i] == 0){
n++;}
}
int m = 0;//判断0的数量，
length = oldArr.Length - n;//得到长度12
int[] newArr = new int[length];//新定义一个数组
//这个是新数组的下标
for (int i = 0; i < length; i++)
{
//这个是旧数组的下标
//假设i=6,则m=2,所以newArr[6]=oldArr[8]
//此时newArr数组存了：1,3,4,5,6,6
for (int k = i + m; k < oldArr.Length; k++)
{
if (oldArr[k] == 0)
{
m++;
continue;
}
newArr[i] = oldArr[k];
break;
//若这里不中断for循环，
//k就一直加到旧数组长度，newArr[i]就一直变换
}
}
for (int j = 0; j < length; j++)
{
Console.Write(+newArr[j] + " ");
}
int[] oldArr = {
1, 3, 4, 5, 0, 0, 6, 6, 0, 5, 4, 7, 6, 7, 0, 5 };
int num = 0;
for (int i = 0; i < oldArr.Length; i++)
{
if (oldArr[i] == 0)
{
num++;
}
}
int[] newArr = new int[oldArr.Length - num];
int t = 0;
for (int i = 0; i < oldArr.Length; i++)
{
if (oldArr[i] == 0)
{
}else{
//将不为0的数放在新数组中
newArr[t]=oldArr[i];
t++;
}
}
for (int i = 0; i < newArr.Length; i++)
{
Console.Write(newArr[i]);
}