In-depth understanding of the underlying mechanism of arrays in Go language

The underlying implementation principle of arrays in Go language

The storage structure of arrays

The array in Go language is a continuous memory block, in which Each element occupies a fixed size of space. The element type of an array can be any basic data type or a custom type. The length of an array is fixed, specified when the array is created, and cannot be changed later.

The underlying implementation principle of an array is to use a continuous memory space to store the elements of the array. The first element of the array is stored at the starting address of the memory space, and the last element is stored at the end address of the memory space. There are no gaps between the elements of the array, so the total size of the array is equal to the size of the array elements multiplied by the length of the array.

For example, the following code creates an array containing 10 int type elements:

var arr [10]int

The underlying implementation principle of this array is as follows:

+---+---+---+---+---+---+---+---+---+---+
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
+---+---+---+---+---+---+---+---+---+---+

The first element of the array It is stored at the starting address 0 of the memory space, and the last element is stored at the end address 9 of the memory space. There are no gaps between the elements of the array, so the total size of the array is equal to the size of the array elements (4 bytes) multiplied by the length of the array (10), which is 40 bytes.

Array access

The elements of the array can be accessed by index. The index of an array is an integer that represents the position of an element in the array. The first element of the array has an index of 0, and the last element has an index of the length of the array minus one.

For example, the following code accesses the first element of the array arr:

fmt.Println(arr[0])

This code will output 0 because the first element of the array arr is 0.

Traversal of arrays

Arrays can be traversed through a for loop. The variable in the for loop can be the index of the array or the element of the array.

For example, the following code traverses the array arr and outputs each element:

for i := 0; i < len(arr); i++ {
    fmt.Println(arr[i])
}

This code will output:

0
1
2
3
4
5
6
7
8
9

Comparison of arrays

Arrays can be passed Compares the elements of an array to compare. The comparison rules for arrays are as follows:

• If the lengths of the two arrays are different, the shorter array is compared first.
• If the lengths of two arrays are the same, the comparison starts from the first element.
• If the elements of the two arrays are the same, continue to compare the next element.
• If the elements of the two arrays are different, the comparison result is false.

For example, the following code compares array arr and array br:

var arr = [10]int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
var br = [10]int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}

fmt.Println(arr == br)

This code will output true because the elements of array arr and array br are the same.

Copy of array

Arrays can be copied through the copy function. The syntax of the copy function is as follows:

func copy(dst, src []Type) int

Among them, dst is the target array and src is the source array. The copy function will copy the elements of the src array to the dst array. If the length of the dst array is less than the length of the src array, only the length elements of the dst array are copied.

For example, the following code copies the array arr to the array br:

var arr = [10]int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
var br = [10]int{}

copy(br, arr)

fmt.Println(br)

This code will output:

[0 1 2 3 4 5 6 7 8 9]

Slices of the array

The array can be passed Slice to create subarrays. The syntax of slicing is as follows:

arr[start:end]

Among them, start is the starting index of the subarray, and end is the ending index of the subarray. If start is omitted, the starting index of the subarray is 0. If end is omitted, the end index of the subarray is the length of the array.

For example, the following code creates a subarray of the array arr:

var arr = [10]int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
var subArr = arr[2:5]

fmt.Println(subArr)

This code will output:

[2 3 4]

Summary of the array

Arrays are in the Go language An important data structure. The underlying implementation principle of an array is to use a continuous memory space to store the elements of the array. The elements of an array can be accessed by index or iterated through a for loop. Arrays can be compared by comparing the elements of the array, or copied using the copy function. Arrays can be sliced ​​to create subarrays.

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