How to set up golang slices

Golang is one of the programming languages ​​that has attracted much attention in recent years. It not only has high efficiency and excellent concurrent processing capabilities, but also has many advantages such as being easy to learn and concise syntax. As one of the important components of Golang, slices are often used in development. So, how to set up slices in Golang? Let’s take a closer look below.

What is slicing?

In Golang, a slice is a data structure similar to an array, but it has higher flexibility and variability. A slice can be regarded as a dynamic array, the length is not fixed, and elements can be added or deleted at will. The underlying structure of a slice is similar to an array, but it is not fixed-length but can be dynamically expanded.

The definition and use of slices

It is very simple to define a slice in Golang. Just use "[]" to declare it. The syntax format is as follows:

var a []int //Define an int type slice a

You can also use the built-in make function to create a slice with an initial capacity of 0, as follows:

a := make([]int , 0) //Create an int type slice with an initial capacity of 0

It can be seen that the first parameter of the make function is the type of the corresponding slice, the second parameter is the length of the slice, and the third parameter The argument is the capacity of the slice (optional). The length represents the number of elements currently in the slice, and the capacity represents how many elements the slice can currently store.

Next, we can add elements to the slice through the append function, as follows:

a = append(a, 1) //Add element 1 to slice a

The append method here is a built-in function in Golang, which can be used to add elements to the slice. After adding, the elements in slice a change from 0 to 1.

Assignment and copying of slices

In Golang, the assignment and copying of slices are quite easy. They are pointers to the underlying array, so when assigning or copying, just copy the slice pointer. copies without making a copy of the underlying array.

The following is an example:

a := []int{1,2,3} //Define a slice a
b := a //Assign a to b
b[0] = 4 //Modify the value of slice b to [4 2 3]
fmt.Println(a) //Output the value of a to [4 2 3]

You can see , after assigning a to b, modifying the elements in b will affect the value of the elements in a. Conversely, modifying an element in a will also affect the value of an element in b. This is because a and b point to the same underlying array.

Of course, if you need to copy a slice without changing the original array, you can use the copy function to make a deep copy, as follows:

a := []int{1,2, 3}
b := make([]int, len(a))
copy(b, a) //Copy the value of slice a to slice b
b[0] = 4
fmt.Println(a) //The value of output a is [1 2 3]
fmt.Println(b) //The value of output b is [4 2 3]

You can see , after using the copy function to copy the value of slice a to slice b, modifying the elements in b will not affect the value of the elements in a.

Slice expansion

Slice expansion means that when the slice capacity is insufficient, it needs to be dynamically expanded to accommodate more elements. When the slice capacity is insufficient, Golang will reallocate a larger memory space at the bottom and copy the elements in the original slice to the new memory.

When a slice is expanded, Golang will try to expand according to the following rules:

1. If the new length is less than or equal to 2 times the original length, the capacity of the new slice will be the original length. 2 times.
2. Otherwise, the new slice capacity is the length plus 1.

The following is an example:

a := []int{0, 1, 2, 3 , 4, 5, 6, 7, 8, 9}
fmt.Println(len(a), cap(a)) //Output: 10 10

a = append(a, 10) //Add an element
fmt.Println(len(a), cap(a)) //Output: 11 20

As you can see, after adding element 10 to the slice, the capacity expands At 20, it is twice the original length.

Summary

Slices in Golang are a very practical data structure that have similar characteristics to arrays, but are more flexible and changeable. When using slices, we need to understand the basic knowledge of slice definition, assignment, copying, and expansion, and make reasonable applications based on actual needs. I believe that through the introduction of this article, readers should have a deeper understanding of slicing settings in Golang.

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