How to set up slices in Go

As a statically typed language, Go language has a large number of slicing operations during development. A slice is a container that can store a sequence of elements of a certain length, and its length can be dynamically expanded or reduced at runtime. In this article, we will explore how to set up slicing in Go.

1. Create a slice
In Go, you can use the make() function to create a slice. The make() function requires two parameters: slice type and slice length. For example, to create an integer type slice of length 5, you can write:

slice := make([]int,5)

If we need an integer type slice that has been allocated storage space, you can use the following method:

array := [5]int{1,2,3,4,5}
slice := array[1:4]

The array here is an array containing 5 integer elements, and the slice is a slice from the second element to the fourth element of the array. You can use the len() function to get the number of elements of the slice, and the cap() function to get the current maximum capacity of the slice.

2. Slice expansion
When the number of elements stored in a slice exceeds its current maximum capacity, the slice will automatically expand. During expansion, the slice length doubles and the capacity triples. For example, if a slice with a length of 10 and a capacity of 20 is to be expanded again, the slice length will become 20 and the capacity will become 40.

Although Go's slices are dynamically expanded, this does not mean that the slice length can be doubled every time, because doing so may result in insufficient continuous memory space. When the current memory cannot be expanded, a new memory block will be reallocated and the original elements will be copied to the new memory block. This is a resource-intensive operation.

3. Slicing and splicing
In the Go language, slicing and splicing operations are very common. One or more slices can be spliced ​​together using the append() function. The append() function is a variable parameter function, each parameter can be one or more slices to be spliced.

For example, we want to splice two slices with a length of 3 into a slice with a length of 6, which can be written as:

slice1 := []int{1,2,3}
slice2 := []int{4,5,6}
slice3 := append(slice1,slice2...)

It should be noted that the slice passed to the append() function They must be of the same type, otherwise they will not be spliced. In addition, uninitialized slices cannot use the append() function directly and must first be initialized using the make() function.

4. Slice copy
In Go language, you can use the copy() function to copy slices. The copy() function can copy the elements of one slice to another slice. It is usually used to copy the elements of one slice to another slice. The first parameter of the copy() function is the target slice, and the second parameter is the source slice. For example, if we want to copy a slice of length 5 to another slice, we can write:

slice1 := []int{1,2,3,4,5}
slice2 := make([]int,5)
copy(slice2,slice1)

In the above code, slice2 will copy the elements of slice1. It should be noted that the target slice must be initialized using the make() function, otherwise the copy operation will not be possible.

Summary:
Slicing is a very important data type in the Go language and is widely used in various scenarios. This article briefly introduces how to create slices, how to expand, how to splice and copy. For slicing operations, you need to pay attention to the use and utilization of memory, and also pay attention to the prevention of boundary problems.

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