Array is declared and used

Array

An array is a sequential collection of fixed sizes that store elements of the same type. An array is a collection used to store data and is generally considered to be a collection of variables of the same type.

Declaring array variables is not a separate variable that declares number0, number1、...、number99, but rather a variable like numbers, and then uses number 、...、s. A specified element in the array is accessed through an index.

All arrays are made up of continuous memory locations. The lowest address corresponds to the first element, and the highest address corresponds to the last element.

Declare the array

To declare an array in C#, you can use the following syntax:

datatype[] arrayName;

Among them,

• Datatype specifies the type of element that is stored in the array.
• [ ] Specifies the rank (dimension) of the array. Rank specifies the size of the array.
• ArrayName specifies the name of the array.

For example:

double[] balance;

Initialize the array

Declaring an array does not initialize the array in memory. When you initialize an array variable, you can assign a value to the array.

The array is a reference type, so you need to use the new keyword to create an instance of the array.

For example:

double[] balance = new double[10];

Assign an assignment to an array

You can assign a separate array element by using an index number, such as:

double[] balance = new double[10];
balance[0] = 4500.0;

You can assign values to arrays while declaring them, such as:

double[] balance = { 2340.0, 4523.69, 3421.0};

You can also create and initialize an array, such as:

int [] marks = new int[5]  { 99,  98, 92, 97, 95};

In these cases, you can also omit the size of the array, such as:

int [] marks = new int[]  { 99,  98, 92, 97, 95};

You can also assign an array variable to another target array variable. In this case, the target and source point to the same memory location:

int [] marks = new int[]  { 99,  98, 92, 97, 95};
int[] score = marks;

When you create an array, the C# compiler implicitly initializes each array element as a default value based on the array type. For example, all elements of an int array are initialized to 0.

Access array elements

Elements are accessed by indexed array names. T his is achieved by placing the index of the element in square brackets behind the array name. For example:

double salary = balance[9];

Here is an example that uses the three concepts mentioned above, namely declaration, assignment, access to arrays:

using System;
namespace ArrayApplication
{
   class MyArray
   {
      static void Main(string[] args)
      {
         int []  n = new int[10]; /* n 是一个带有 10 个整数的数组 */
         int i,j;


         /* 初始化数组 n 中的元素 */         
         for ( i = 0; i < 10; i++ )          
         {             
            n[ i ] = i + 100;          
         } 
            
         /* 输出每个数组元素的值 */          
         for (j = 0; j < 10; j++ )          
         {             
           Console.WriteLine("Element[{0}] = {1}", j, n[j]);          
         }          
         Console.ReadKey();       
       }    
    } 
} 

When the above code is compiled and executed, it produces the following results:

Element[0] = 100
Element[1] = 101
Element[2] = 102
Element[3] = 103
Element[4] = 104
Element[5] = 105
Element[6] = 106
Element[7] = 107
Element[8] = 108
Element[9] = 109

Use the foreach loop

In the previous example, we used a for loop to access each array element. You can also use a foreach statement to traverse the array.

using System;

namespace ArrayApplication
{
    class MyArray
    {
        static void Main(string[] args)
        {
            int []  n = new int[10]; /* n 是一个带有 10 个整数的数组 */


            /* 初始化数组 n 中的元素 */
            for ( int i = 0; i < 10; i++ )
            {
                n[i] = i + 100;
            }           /* 输出每个数组元素的值 */          
            foreach (int j in n )
            {
                int i = j - 100;
                Console.WriteLine("Element[{0}] = {1}", i, j);
                i++;
            }
            Console.ReadKey();
        }
    }
}

When the above code is compiled and executed, it produces the following results:

Element[0] = 100
Element[1] = 101
Element[2] = 102
Element[3] = 103
Element[4] = 104
Element[5] = 105
Element[6] = 106
Element[7] = 107
Element[8] = 108
Element[9] = 109

Array details for C#

Arrays are very important in C# and need to know more details. Here are some important concepts related to arrays that programmers must be aware of: