Let's talk about the application scenarios of variable-length arrays in golang

As various application scenarios continue to emerge, more and more developers are beginning to choose Go language as their main development language. As a modern static language, Go language has many features and is outstanding in high concurrency and network programming. Among them, variable-length arrays (slices) are considered to be one of the most important and effective data types in the Go language. Therefore, this article will use variable-length arrays as the theme to explore in detail its various application scenarios in the Go language.

What is an array of variable length?

Indefinite length array, also called slice. It is a dynamic array whose length is not fixed and can grow as the number of elements increases. A slice is composed of a pointer to the array, the slice length and the slice capacity, where the capacity represents the maximum length that the slice can occupy without expanding the underlying array.

Before Go language, other static languages ​​such as C and C language also had the concept of dynamic arrays. In the Go language, a slice is not only a pointer to the underlying array, but also stores the length and capacity of the slice. The advantage of this design is that it not only makes it easy to obtain the length of the array, but also makes memory management more convenient. At the same time, using a large array for a long time may cause a lot of waste of memory, while slicing can gracefully expand and shrink when needed, thus saving memory space.

The definition and operation of slices

There are many ways to define slices. The commonly used methods are as follows:

// 第一种方式：使用 make 函数
var s1 []int = make([]int, 5, 10)

// 第二种方式：使用简化方式
s2 := []int{1, 2, 3, 4, 5}

// 第三种方式：定义数组，使用切片方式取出其中一部分
a := [5]int{1, 2, 3, 4, 5}
var s3 []int = a[1:3]

The main operations on slices are as follows:

1. Slice expansion
   The number of elements in the slice exceeds its capacity, and additional space needs to be allocated. At this point, a new underlying array will be created, the values ​​of the original array will be copied to the new array, and then the original slice will be pointed to the new array again.
2. Append elements to slices
   To add elements at the end of the slice, you need to re-apply for memory at the end of the slice and insert the new elements into it.
3. Slicing to delete elements
   When slicing deletes elements, it only needs to move the element after the subscript of the element to be deleted forward one position.

In addition, since the underlying layer of the slice is an array, in the Go language, you can use a for-range loop to traverse and operate the elements in the slice, for example:

for _, ele := range s1 {
    fmt.Println(ele)
}

Slice application scenario

Slices, as dynamic arrays, have the following application scenarios:

1. Ordered collections
   Slices can store elements of the same type in sequence, such as int, float, etc., thus achieving ordering Collection effect. Slicing can quickly add and delete elements, and also supports operations such as fast query and sorting.
2. Instead of Array
   An array is a fixed-length data structure, while slicing can increase or decrease the number of elements as needed. Therefore, in Go language, slices are often regarded as a more practical form of arrays.
3. Passing parameters
   Slicing is very efficient in both pointer and value passing, so it can be more convenient and efficient when passing data between functions.

Summary

Variable length arrays (slices) are very practical in the Go language and have many features such as dynamic addition and deletion of elements. At the same time, it is very simple to use and can replace the array form. In actual development, slicing is widely used in various scenarios such as memory management, lists, and collections. It is one of the most important data types in Go language development.

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